Abstract: A polymer ejector system for reducing drag on an external surface of an urwater vessel includes a base portion mounted in an exterior surface of the underwater vessel, the base portion including an arcuate inner wall. A flexible lip portion is positioned above the base portion and spaced apart therefrom. The lip portion has an outer surface substantially coplanar with an outer surface of the underwater vessel, an arcuate inner wall, and is tapered at a distal end of the lip. This lip may be actively moved by means of MEMS deposited electrodes to control the passageway mentioned next. A passageway is formed between and defined by the inner wall of the lip and the inner wall of the base portion, such that the passageway terminates at the outer surface of the underwater vessel and substantially tangent thereto. The ejector may be constructed from single crystal silicon by so called MEMS (Micro-Electro-Mechanical Systems) methods.

Abstract: A drag-reduction system incorporated within an inwardly stepped underside of a boat hull for reducing a degree of water pressure forces exerted upon the boat hull during travel of the boat upon a body of water. A plurality of spaced apart rollers are secured at a generally aft location of the boat hull associated with the inwardly stepped underside and extend in parallel spaced apart fashion and perpendicularly to a longitudinal water flow across the boat hull experienced during propulsion of the hull. An elongate and planar shaped belt of a water impervious material having an established width and defining a continuous extending and closed loop is mounted over the plurality of spaced apart rollers. A first linearly extending location of the continuous belt is recessed within the stepped underside of the hull and a second linearly extending location is in contact with the longitudinal water flow.

Abstract: A robust, nontoxic, antifouling coating and bulk material and process for king the same are disclosed. The antifouling coating comprises a basecoat formed typically from a polyol and a poiyiisocyanate wherein a molar excess of poiyiisocyanate is typically used. A topcoat is formed on the basecoat by reacting the basecoat with aliphatic branched or unbranched mono-alcohol or polyol.

Abstract: Magnetic and electric fields are used in a controlled manner to create Lorentz forces that affect the flow of a conductive fluid near the boundary layer of a control tile, or a matrix of control tiles, immersed in a conductive fluid. The control tiles are combined to form control cells, with each control cell including a pair of electrodes and at least one permanent magnet. The pair of electrodes are coupled to a current source which biases the electrodes to cause an electrical current to flow from a positive electrode (anode), through the conductive fluid in which the cell electrodes are immersed, to a negative electrode (cathode). The current source is time multiplexed to better control the direction of the current flow between adjacent electrodes. The permanent magnet(s) generates a magnetic field which interacts with the electrical current to create a Lorentz force that influences the flow of the conductive fluid, near the boundary of the control tile, e.g.

Abstract: A flow control system is used to control fluid flow at the boundary layer an object or body about or within which the fluid flows relative to the body. The flow control system includes an actuated membrane that is displaced in a direction substantially tangential to the actuated membrane, thereby causing a disturbance or modified shear stress distribution in the boundary layer fluid flow. One or more sensor elements are disposed proximate a top region of the actuated membrane for sensing fluid conditions at the boundary layer flow. A membrane actuator provides the displacement, for example, by extending or contracting the actuated membrane in a direction substantially tangential to the actuated membrane. A feedback device is responsive to a system of sensor elements and is coupled to a system of membrane actuators to cause the displacement in one or more regions of the actuated membrane in response to the sensed fluid conditions.

Abstract: A human powered marine vehicle is provided having a rigid front section and a flexible rear section which may be flexed at at least two point therealong. The arms and/or legs of one or more persons in the vehicle are used to power actuators for each flex point, which actuators are operated so as to provide a predetermined relationship, and in particular at least a predetermined phase relationship, between flexure at the various points so that the flexible section moves with a wave or fish-like motion. The person(s) operating the vehicle is trained so as to maintain the predetermined relationship and various techniques are disclosed to assist the operator(s), or otherwise facilitate, the maintenance of the desired relationship.

Abstract: A method for controlling microturbulence in a medium flowing near a surface s disclosed. The method includes the steps of measuring the forces acting near or on the surface and using those measurements to determine the state probabilities for the microturbulent events occurring at the surface. The control method then activates selective cells in an array of cells to apply forces at the surface to counteract the microturbulent events and thus reduce turbulence. Each cell has a pair of electrodes and opposing magnetic poles such that when the control method activates a cell, the interaction of the electric field and the magnetic field at the cell creates a Lorentz force normal to the surface.

Abstract: A marine structure submersible in seawater, such as a hull, which when electrically activated is then resistant to fouling by marine organisms. The hull is formed by a structural laminate having a core sandwiched between inner and outer skins. The outer skin which forms the exposed surface of the hull is coated with a metallic paint defining a cathodic electrode. The core is constituted by balsa wood or foam plastic modules attached to an open-mesh scrim that includes conductive fibers to create an electrical grid defining an anodic electrode that is embedded in the laminate. Impressed across the electrodes is a direct voltage to establish an electric field causing marine organisms which seek to foul the hull surface to migrate away from this surface. Alternatively, the cathodic electrode may be formed by an open-mesh scrim defining an electrical grid interposed between the core and the outer skin.

Abstract: A surface layer for use in connection with an object adapted for motion tugh a fluid includes an array of tiles each having a pair of electrodes and a pair of magnetic poles positioned to generate respective electric and magnetic fields generally transverse to each other. Either or both of the electrodes or magnetic poles are controllable to provide adjustable electrical and/or controllable magnetic fields. A plurality of turbulence sensors is provided each located proximate to and generally upstream of a tile. Each turbulence sensor generating a turbulence signal representative of fluid turbulence proximate thereto. A control circuit for controlling the electrical field generated by the electrodes and/or the magnetic field generated by the magnetic pole in relation to the turbulence signal from the turbulence sensors, thereby to generate a Lorentz force for controlling the fluid.

Abstract: A method of protecting a hull of a marine craft from adhesion of marine growths and inorganic deposits includes a step of applying protective covering sheets to the hull in a pattern that provides substantially complete coverage of at least the portion of the external surface that is submerged during normal use. The sheets have an outer surface consisting essentially of a polymer such as PTFE that resists adhesion of marine growths and inorganic deposits, and an inner surface comprising a water-resistant adhesive effective to secure the sheets to the outer hull surface and prevent the sheets from coming off. The invention further provides a boat hull or other outdoor structure or vehicle that is protected with sheets according to the described method.

Abstract: A method and apparatus for providing reduced drag on a body moving in a direction D through a selected fluid medium at a speed U which is normally sufficient to cause turbulence. Reduced drag is generally accomplished by flexing at least the outer surface of at least the rear third of the body to produce a wave-like motion of the body having a wavelength of between 0.5 and 2.0 times the length of the body, a reduced frequency value .OMEGA. between 0.1 and 0.5 and a time delay between successive points on the body reaching peaks for their flex motion which is directly proportional to the distance x.sub.i in the direction D of the point from a reference point on the body and inversely proportional to the phase speed c.sub.p of the wave. A variety of techniques are described for achieving the desired wave-like motion.

Abstract: A marine anti-fouling system and method for inhibiting the growth of marine life on a submerged surface includes a control box and a number of transducers. The control box further includes a ultrasonic driver board, a magna-polar filter, and a power source. The ultrasonic driver board generates an electrical signal having an ultrasonic frequency which continually varies between 25 KHz to 60 KHz. A portion of this continually varying electrical signal is passed through the magna-polar filter where the signal is enhanced. This enhanced signal is then returned to the ultrasonic driver board where it is combined with the electrical signal varying between 25 KHz and 60 KHz. This combined signal is then electrically communicated to a number of transducers which are mounted on the submerged surface to be protected.

Abstract: An improved aquatic sports board is provided. The rail of the board is equipped with a plurality of apertures which are arranged in a pattern along the length of the rail. The apertures serve to reduce the drag on the bodyboard as it moves through the water.

Abstract: An underwater vehicle has a generally cylindrically portion with boundary yer polymer fluid storage and a pressurizing source provided therein, and a nose portion secured to the cylindrical portion and capable of being reconfigured for ejecting the polymer fluid from the nose adjacent the centerline of the vehicle or from the area of minimum pressure adjacent the juncture between the nose of the vehicle and the cylindrical portion. The nose portion can be reconfigured without breaking down the joint between the nose portion and the cylindrical portion of the vehicle. A removable plug is provided for isolating nose ejector ports, and a removable channel blocking dam is provided for isolating the ports provided in the area of minimum pressure adjacent the joint between the nose portion and the cylindrical portion of the vehicle. Further, the nose ejector ports are defined in a removable nose cap subassembly and a removable annular subassembly defines the ejector ports in the area of minimum pressure.

Abstract: A surface effect hull particularly suitable for use with a catamaran vessel. The twin hulls each comprise a V-shaped portion and a recess portion that receives pressurized gas therein. The V-shaped bow portion create dynamic lift and the pressurized air portion creates an air cushion for reduction of drag.

Abstract: A stem duct of a ship used to achieve the reduction of the ship's propulsion wave height and the improvement in the laminarity of the flow around the ship's bow, so that the ship is able to move with an increased speed and/or with reduced fuel consumption. The duct is mounted on each side of the bow frontal surface and has an airfoil section fitted, arranged in the direction of the flow, with its leading edge at the duct inlet and its trailing edge at the duct outlet. Following mounting of the duct, a passage is created for the flow, between the duct's interior surface, consisting of the convex airfoil surface, and the ship's bow surface. The flow passing through the passage acquires an increased speed and a reduced pressure, thereby leading to an improved slip of the ship.

Abstract: A spray suppressor for an air cushion vehicle comprising inflatable loop elements fixed to the air cushion seal finger sleeves and positioned immediately outward from the air cushion boundary. The elements are pressurized to a pressure less than the air cushion and greater than the ambient pressure to capture spray and supplement the seal performance.

Abstract: A boat having a pair of hull members with separate fore and after planing surfaces. Each one of the hulls has a forebottom surface, an aftbottom surface and a midbottom surface. The forebottom surfaces and the aftbottom surfaces have positive trim angles. Each midbottom surface is recessed into the respective hull member. When propelled at planing speeds, the boat skims across the water upon a planing area of the forebottom surface and a planing area of the aftbottom surface with the midbottom surface lifted out of the water.

Abstract: A concentrated slurry comprises a high molecular weight polymer, a carrier, wetting agent, and dispersant. The slurry is characterized by its ability to reduce turbulent flow and skin friction thereby reducing drag of a vessel when the slurry is mixed with water and dispersed in a thin sheet along the surface of a vessel.

Abstract: A paint for application to the exterior surface of waterborne vehicles indes a high molecular weight water soluble polymer with drag reducing properties which time releases into the fluid boundary layer immediately adjacent the vehicle surface to reduce turbulence and promote laminar flow.

Abstract: The speed of a high-speed powered boat such as high-speed fisherboats can be increased even at the same power output of the engine irrespective of the speed by providing on each side symmetrically with a plural number of fins each opening outwardly toward the rear end making an angle with the boat hull in at least two high and low rows along the waterline which varies depending on the speed of the boat, whereby the wave-making resistance against the boat is greatly reduced at varied speed of the boat along with a stabilizing effect to decrease rolling. The effect of wave-making resistance suppression can be further enhanced by providing the bow of the boat with a stem-edge guard with right and left wings opening outwardly toward the side lines.

Abstract: A method of controlling the attachment of organisms to an underwater surface is disclosed. The method comprises contacting the organisms with a compound of Formula I ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 are each independently hydrogen, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.3 alkoxy, halogen, or hydroxyl. Antifouling coatings and cementitious compositions containing a compound of Formula I are also disclosed.

Abstract: A rotor type energy saving apparatus mounted on the bow of a ship is disclosed for reducing the water resistance against the bow of a ship and converting the linear movement of waves into rotational movement to obtain an impelling force. Application of the apparatus results in a decrease in the amount of energy required to propel the ship. The apparatus has a conical shaped outer shell with blades running along its length and an inner means allowing the device to freely rotate. The apparatus is useful in reducing resistance and providing an impelling force on a variety of ships. It is best suited for use on small ships which have lengths under 45 meters.

Abstract: A self-propelled torpedo with four stabilizer fins having an "X" orientat when the torpedo is running submerged through water. Each stabilizer fin has a fixed leading section and a trailing rudder section with a rigid trailing edge. Bands of tape are wrapped fore and aft around each rudder section to provide opposed trailing extensions of tape which are adhered together and slitted to form a trailing extension of flexible material with separate strips along the full length of the rigid trailing edge. The trailing extension of flexible material provides for shedding trailing edge vortexes downstream for reducing the transmission of vortex energy upstream to the rudder.

Abstract: An improved aerodynamic surface for the exterior of vehicles moving through a gas and vehicles employing such improved surfaces. The improved surface comprises a matrix of dimples or depressions formed into the portions of the surface of the vehicle. The improved surface is most beneficially located either at a leading edge, where the vehicle first cleaves the pool of air through which it is traveling, or on vehicle surfaces which tend to move the air pool to accommodate the presence of the vehicle itself or on vehicle surfaces to which the designer wishes to provide a lift function. Wings, ailerons and rudder surfaces are examples of surfaces to which a lift function is most applicable. The vehicle may be of the nature of an automobile, a boat or an airplane. The invention is also applicable to the internal surface of pipes for conveying fluid.

Abstract: On a body, for example a stabilizer fin or a rudder blade on ships or the keel fin on sailboats with a keel, which is fastened to a support body, preferably a ship's hull, so that it projects outward, several ribs are fastened so that they project on the exposed end of the body. These ribs are located at some distance from one another and are parallel to the plane of symmetry of the body. The length of the ribs is approximately 1/10 to 1/20 of the length of the body, which eliminates or reduces turbulence which occurs at the end of the wing like structure.

Abstract: Electrodes and magnets are disposed in alternating relation on confronting urfaces of microgrooves that respectively produce electric and magnetic fields that are cooperative to provide a force that acts along a flow direction defined between a vessel and a relatively moving medium to controllably diminish turbulence generation in seawater.

Abstract: To reduce the total ship resistance and to improve a propeller efficiency and cavitation performance due to the reduced thrust loading on the propeller for ships or vessels having a sonar dome or an equivalently shaped designs located below the baseline of the hull, a teardrop-shaped bulbous bow is attached to the ship stem bow between the forward perpendicular of the bow and 12.7 ft forward of the forward perpendicular of the vessel, inclusive, and between the ship design waterline and the baseline. The bulbous bow is separate and discrete, and spaced from the sonar dome and has a shaped of a teardrop. The teardrop shaped bulbous bow is mounted to the ship stem bow with the round end portion pointing in the forward direction and the pointed end portion pointing in the aft direction.

Abstract: A process for protecting a rigid substrate against aquatic fouling comprises coating the substrate with an elastomeric undercoat as a 200 to 1500 micron thick layer and with a top coat of a room temperature vulcanisable silicone rubber. The elastomeric undercoat is generally harder than the room temperature vulcanisable silicone rubber foul resistant top coat and preferably has a Shore A hardness of 60 to 90 and an extensibility of 200 to 800%. The abrasion and tear resistance of the silicone rubber foul resistant layer is markedly increased by the use of the elastomeric undercoat.

Abstract: Fluid friction of a body moving through air or water is reduced by means of a plurality of symmetrical depressions on the surface of the body. The symmetrical depressions are closely spaced but not quite abutting. The symmetrical depressions are sized in proportion to the width of the body. For a cylindrical body, each symmetrical depression is between one fiftieth and one fortieth of the diameter of the body. The symmetrical depressions are shallow, ten to twenty times wider than they are deep. The symmetrical depressions are shaped like sections of truncated cones, or hexagonal prisms, or geodesic domes. The symmetrical depressions cover virtually the entire surface of the body.

Abstract: The bottom and side surfaces of a water sports board are textured with dimples measuring four to six thousands of an inch deep and a density of 80 to 160 dimples per square inch.

Abstract: An air cushion displacement hull water vehicle has a novel construction so s to defrictionize water flowing under the hull as the vehicle is propelled through the water. The hull includes a forward bow portion, an opposing aft end portion, a pair of sidewalls spaced from each other and extending between the forward bow portion and the aft end portion, and a bottom wall extending between the forward bow portion and the aft end portion and between the pair of sidewalls. The bottom wall of the hull is recessed to define an air cushion region. An air supply device positioned within the interior of the hull communicates with the air cushion region and is operable to supply pressurized air to the air cushion region to defrictionize water flow under the air cushion region.

Abstract: The wave making resistance on a proceeding ship can be greatly decreased by providing the ship hull with at least one pair of fins mounted on the hull extending above and below the draft line, each fin being fixed at the front end line and the rear end of the fin outwardly extending making a certain fin-mounting angle of 2 to 25.degree. with the hull surface.

Abstract: The current invention relates to an anti-fouling system for substances in contact with seawater which is constituted of the first conductive membrane that is coated on the outer side of the electric insulator mounted at the surface of the substance such as ships, marine structures in contact with seawater and is composed of thin sheets of metals having low specific resistance or metal oxide, spray-coated membrane, evaporated membrane or fused membrane, and the second conductive anti-fouling membrane having higher electric resistance than the first conductive membrane which is coated on the outer side of the above first conductive membrane and which is composed of the oxidation-resistant insoluble substance and the organic binder, and the power supply equipment that supplies direct currents flowing from the first conductive membrane through the second conductive membrane toward the electric conductor made of iron, copper or carbon located in seawater and opposite the second conductive membrane, owing to the co

Abstract: A high polymer suspension including a polymer; a liquid carrier; a fibrous silicate material; and an organic derivative of clay. The polymer is preferably a polyacrylamide, the fibrous silicate material a chrysotile asbestos, and the organic derivative of clay, dimethylbenzloctadecyl ammonium hectorite.

Abstract: The present invention relates to an improved method of protecting the hulls of marine vessels from fouling. The inventive method involves the application of thin metallic films to the hull of a boat. The inventive method includes the use of various techniques for application of the film, techniques for preventing the touching of dissimilar metals, techniques for insuring that dissimilar metals are insulated and isolated from one another, insuring that active or passive cathodic protection systems are not on the same surface plane as the attached films and other techniques. The specific materials which are applied to the vessel hull as well as their various parameters in the environment of the present invention are disclosed. Specific treatments to the thin metallic film to improve the adherence of these thin film hulls and adjacent films are disclosed.

Abstract: A dispenser for ejecting slurry into a liquid stream so that optimum mixing s attained. This dispenser may include an elongated body having nose and main sections, the forward end of the main body section having an annular slurry receiving cavity which is located adjacent the nose. Means are provided for mounting the nose to the main body section for longitudinal movement so as to open and close the annular cavity to the liquid stream. In this manner the slurry can be ejected and dispersed into the liquid stream when the annular cavity is opened thereto. In order to obtain controlled mixing the dispenser may further include a conduit in which the elongated body is disposed.

Abstract: Hydrofoil craft, particularly a method of economically modifying a conventional hull by means of foils to obtain enhanced lift and rough water stability. The method is characterized by defining an axial tunnel(s) intermediate the bow and transom of a catamaran hull or V-bottom hull modified with chine mounted aerofoils; positioning a flexible dihedral foil beneath the water line and on either side of the bow so as to obstruct and create a turbulence in the forward end of the tunnel, while cushioning shock and lifting the bow; and simultaneously enclosing the transom end of the tunnel with a foil, so as to compress the turbulence and lift the transom.

Abstract: An aerodynamic or hydrodynamic surface is provided with so-called "riblets" for reducing drag by modification of the turbulent boundary layer. The riblets comprise flow-aligned elongate projections of small height. In order to increase their effectiveness in reducing drag, just those parts of the riblets which extend above the height of the virtual surface--established by the riblets themselves due to their displacing the turbulent motion away from the real surface--exhibit an abrupt transition to a cusp-shaped profile which more effectively promotes very small scale flow-aligned vortices which drain energy from the larger drag-inducing low speed flow-aligned vortices or "streaks" in the boundary layer.

Abstract: A water vehicle includes a longitudinally elongated hull having a first portion adapted to separate the water by movement of the hull through the water. Foam is generated by the separation of the water. A second portion of the hull is adapted to contain the foam underneath the hull. The vehicle will be supported during propulsion at least in part by a surface of the foam.

Abstract: Since the superstructure of ships are often very high and bulky they cause a high air resistance to the forward movement of the ship which results in a high fuel consumption of the ship. In order to reduce the air resistance to the forward movement of the ship, a special type of air deflector is arranged in front of the superstructure, which is of such a design that it can be easily fitted and removed at will.

Abstract: Arrays of parallel, substantially fore and aft oriented vortex generators are positioned on the keel and rudder of a sailboat to induce vortices at the surfaces of the keel and rudder for the purpose of reenergizing the boundary layers in the water flow past the keel and the rudder to increase the lateral lift in the horizontal plane and to thereby avoid increase in drag associated with keel and rudder stall at high angles of attack with the relative water flow. Similar arrays for the same purpose may be attached to other underwater stabilizing members such as skegs, keel winglets, centerboards, etc.

Abstract: The turbulent drag is reduced on the surface of a body moving through a fluid by providing longitudinal channels in the surface, for example of an aircraft wing, which channels extend in parallel to the flow direction and which channels are interconnected with the boundary layer by a longitudinal gap communicating the channel with the boundary layer.

Abstract: The invention is a system of flow control devices which result in reduced skin friction on aerodynamic and hydrodynamic surfaces. The devices cause a breakup of large-scale disturbances in the boundary layer of the flow field. Referring to FIGS. 1 and 2, the riblet device 10 acts to reduce disturbances near the boundary layer wall by the use of longitudinal striations forming vee-shaped grooves. These grooves are dimensional on the order of the wall vortices and turbulent burst dimensions 31 depicted in FIG. 3. The large-eddy breakup device 41, depicted in FIGS. 4 and 5, is a small strip or airfoil which is suspended in the upper region of the boundary layer. Various physical mechanisms cause a disruption of the large-scale vortices. The combination of the devices of this invention result in a substantial reduction in skin friction drag.

Abstract: A low drag surface construction utilizes a plurality of longitudinally extending, parallel, spaced apart linear vortices extending transversely of the free stream to reduce drag between the free stream and the surface. The surface is provided with stabilizing means which retains the vortices in their relationship with one another but causes them to traverse the surface in the same direction as the free stream but at approximately half the speed. The stabilizing produces a regular variation in boundary flow across the surface and may comprise dynamic means such as sequenced jets of fluid escaping from apertures in the surface.

Abstract: A seagoing vessel is provided with a bow bulb composed of a main body, integral with the vessel's hull and a covering cowl member, which is swingable about horizontal hinges at its rear end. In fully loaded/stationary condition the top ridge of the cowl member just touches the water level. Remotely controlled power motors between the main body and the cowl will raise the forward end of the cowl, so it maintains contact with the occasional water level caused by damming due to the speed of the ship in motion.

Abstract: There is shown apparatus 1 for underwater painting of a substrate 9, comprising a tubular shield 2 having a closed end 3 and an open end 4, and a paint supply device 7 and a compressed air inlet 5. The air inlet 5 passes into a chamber formed between the end 3 and a perforated baffle plate 6 which serves to provide a uniform stream of air under pressure to the open end 4 for displacing water from the substrate 9, which can then be painted using a circular ring of paint issuing from a spray tip 11 of the device 7. The position of the shield can be adjusted using adjustable casters 14, or electronically (means not shown).

Abstract: A marine antifouling material providing an antifouling surface for use in sea water comprises a layer of inert, water-insoluble, flexible and extensible elastomeric carrier material having embedded therein a single layer only of a plurality of copper or copper alloy particles of substantially uniform size and shape exposed at the outer surface of the material to provide a multiplicity of generally evenly sized discrete copper areas in the inert material continuum surface thereof. The particles are insulated from each other and from an opposed inner surface of the material.

Abstract: A torpedo having a nose section wherein the entire nose section is of a porous material. The volume behind the nose is divided into a plurality of annular chambers and a fluid delivery system provides filtered sea water to the chambers for expulsion through the porous nose. The filtered water passing over the nose and torpedo body is at a rate to alter the trajectory of any particulate matter that would tend to destabilize laminar boundary layer operation.

Abstract: Fore and aft headers are parallely spaced apart and connected by a plurality of tubes or pipes extending normal thereto and forming therewith a grid type heat exchanger. The headers are streamlined and fixed to the bottom of a marine vessel with the tubes spaced outwardly from the vessel's bottom and extending longitudinally therewith. The inboard and outboard sides of the tubes are narrowed to define wider entrances and exits between tubes than the spaces between adjacent sides of the tubes intermediate the inboard and outboard sides. The streamlined headers reduce flat plate resistance and resistance due to turbulent water flow to promote laminar water flow therebetween from forward to aft. The widened entrances and exits between tube tops and bottoms accelerates water flow up, around and between tubes by eliminating the "vena contracta" and increasing the flow around adjacent tube sides, thus increasing the rate of cooling of a coolant from an interior heat source.