Abstract: A computer method of simulating a fluid flow in an aircraft environment to determine at least one aerodynamic coefficient, comprising obtaining a first series of values of the aerodynamic coefficient. The method also includes defining a criterion for convergence of said aerodynamic coefficient, selecting a determined set of terms belonging to said first series, defining a monotonic function configured to make a relatively expanding transformation in said determined set relative to the complement of said set, applying said monotonic function on said first series to form a second series of values of the aerodynamic coefficient, determining said aerodynamic coefficient by plotting a variation curve representative of said second series of values of the aerodynamic coefficient, and displaying said variation curve including an intrinsic zoom of the convergence zone of said aerodynamic coefficient.

Abstract: The invention is aimed at a method simulating the aerodynamic flow around an aircraft, so as to detect the aerodynamic loads exerted on a predetermined surface of the aircraft. The method includes a phase of determining a value denoted QA of global dynamic pressure at the level of the predetermined surface of the aircraft. The method includes steps of carrying out simulations of aerodynamic flow around the predetermined surface of the aircraft for given environmental conditions, on the basis of a mesh produced around the shape of the aircraft, determining a local dynamic pressure qA around the predetermined surface of the aircraft, and then calculating the global dynamic pressure QA.

Abstract: A computer method of simulating a fluid flow in an aircraft environment to determine at least one aerodynamic coefficient, comprising obtaining a first series of values of the aerodynamic coefficient. The method also includes defining a criterion for convergence of said aerodynamic coefficient, selecting a determined set of terms belonging to said first series, defining a monotonic function configured to make a relatively expanding transformation in said determined set relative to the complement of said set, applying said monotonic function on said first series to form a second series of values of the aerodynamic coefficient, determining said aerodynamic coefficient by plotting a variation curve representative of said second series of values of the aerodynamic coefficient, and displaying said variation curve including an intrinsic zoom of the convergence zone of said aerodynamic coefficient.

Abstract: A method for predicting the aerodynamic performance of an aircraft element under predetermined conditions, the aircraft element having at least one break at least partially separating two parts that cannot or should not be modeled with a common envelope form, in which: a digital form representative of the form that the aircraft element assumes under the predetermined conditions studied and in which each break is represented, is created, for each break, a totally non-coincident boundary surface at the joining of the two parts is created, and a partial structured meshing around each part is generated, the two partial meshings made in this way being independent of one another, and digital aerodynamic simulation computations using this meshing are carried out with the aid of an aerodynamic computation code capable of processing a totally non-coincident join.

Abstract: A method is disclosed of identifying or fixing the value of the parameters (aerodynamic data) of a pre-determined set of equations forming the aerodynamic models of an aircraft in various configurations, so as to minimize the variance between the values anticipated by using these aerodynamic data, and reference data in cases of known configurations, includes the use of learning or optimization methods to determine at least one portion of the parameters' values. The method includes storing database data, choosing an optimization method or a neural network method, breaking the identification down into several partial identifications, carrying out successive partial identifications, validating the values found for the aerodynamic model's parameters or iterating the method according to a threshold criterion determined on the value of variances between the reference data and the values measured by the identified model.

Abstract: A method of computer simulation of an aerodynamic behavior of an aircraft in flight close to the ground includes generating a volume mesh of a three-dimensional geometric domain. The volume mesh is at least partly delimited by a three-dimensional geometric model of the aircraft and by a plane modelling the ground. The volume mesh defines a computational domain. The method also includes imposing a uniform boundary condition on the plane comprising a predetermined speed vector with a non-zero tangential component and a non-zero normal component, and solving a discrete numerical model of the Navier-Stokes equations by computer on the volume mesh with the uniform boundary condition imposed on the plane to obtain a numerical solution of a fluid flow inside said computational domain.

Abstract: Method for determination of a rigid value of an aerodynamic coefficient of an aircraft, in which measurements are made in a wind tunnel on a model of the said aircraft and, on the basis of these measurements, at least one value, known as flexible model value, of this aerodynamic coefficient is determined, characterized in that a rigid value of the aerodynamic coefficient is calculated on the basis of the said flexible model value(s) and a correction taking into account the flexibility of the model. A plurality of flexible model values is determined on the basis of measurements made by varying the parameter q/E and maintaining the angle of incidence at a constant value, and the correction consists in an extrapolation operation providing a value of the aerodynamic coefficient corresponding to q/E=0. As a variant, a single flexible model is determined and the correction consists in adjusting the said value with the aid of a correction factor.

Abstract: A method and device for determining the width of a safety corridor for an aircraft and to a method and system for securing the automatic low-altitude flight of an aircraft. The device includes an input device which can be used by an operator in order to enter a plurality of errors which each have an impact on the automatic low-altitude flight of the aircraft; a probability determination unit for determining an excursion probability of a safety corridor that is not to be crossed; and a width determination unit for determining the width of said safety corridor form the aforementioned errors and excursion probability, taking account of at least one mathematical expression linking at least the errors, the excursion probability and the width.

Abstract: A method for assessing the aerodynamic ground effects on an aircraft. The method includes determining the variation of at least one aerodynamic coefficient of the aircraft as a function of the height for a range of heights extending from an aerodynamically infinite height to a zero height. In the method, (i) the range of heights is subdivided into at least two consecutive sets of heights; (ii) for one of the sets of heights, the variation of said aerodynamic coefficient is determined by wind tunnel tests using a model of the aircraft; and (iii) for the other of the sets of heights, the variation of said aerodynamic coefficient is determined by digital simulation reproducing by computation the physical reality of the air flow around said aircraft.

Abstract: The invention relates to a method for determination of a rigid value of an aerodynamic coefficient of an aircraft, in which measurements are made in a wind tunnel on a model of the said aircraft and, on the basis of these measurements, at least one value, known as flexible model value, of this aerodynamic coefficient is determined, characterized in that a rigid value of the aerodynamic coefficient is calculated on the basis of the said flexible model value(s) and a correction taking into account the flexibility of the model. A plurality of flexible model values is determined on the basis of measurements made by varying the parameter q/E and maintaining the angle of incidence at a constant value, and the correction consists in an extrapolation operation providing a value of the aerodynamic coefficient corresponding to q/E=0. As a variant, a single flexible model is determined and the correction consists in adjusting the said value with the aid of a correction factor.

Abstract: The invention relates to a method for predicting the aerodynamic performance of an aircraft element under predetermined conditions, the said aircraft element having at least one break (5) at least partially separating two parts (1, 2) that cannot or should not be modeled with a common envelope form, in which: a digital form representative of the form that the aircraft element assumes under the predetermined conditions studied and in which each break (5) is represented, is created, for each break (5), a totally non-coincident boundary surface (7) at the joining of the two parts (1 and 2) is created, and a partial structured meshing around each part (1, 2) is generated, the two partial meshings made in this way being independent of one another, digital aerodynamic simulation computations using this meshing are carried out with the aid of an aerodynamic computation code capable of processing a totally non-coincident join.

Abstract: The invention relates to a method of computer simulation of the aerodynamic behaviour of an aircraft (10) in flight close to the ground. This method is used to identify the slope effect relative to the ground effect. To achieve this, a uniform boundary condition comprising a predetermined speed (UP) with a non-zero tangential component and a non-zero normal component is imposed on a plane (21) modelling the ground; and a discrete numerical model of the Navier-Stokes equations is solved by computer on a volume mesh with said boundary condition imposed on said plane (21), so as to obtain a numerical solution for a fluid flow inside a computational domain defined by said mesh.

Abstract: A method is disclosed of identifying or fixing the value of the parameters (aerodynamic data) of a pre-determined set of equations forming the aerodynamic models of an aircraft in various configurations, so as to minimize the variance between the values anticipated by using these aerodynamic data, and reference data in cases of known configurations, includes the use of learning or optimization methods to determine at least one portion of the parameters' values. The method includes storing database data, choosing an optimization method or a neural network method, breaking the identification down into several partial identifications, carrying out successive partial identifications, validating the values found for the aerodynamic model's parameters or iterating the method according to a threshold criterion determined on the value of variances between the reference data and the values measured by the identified model.

Abstract: A method for assessing the aerodynamic ground effects on an aircraft. The method includes determining the variation of at least one aerodynamic coefficient of the aircraft as a function of the height for a range of heights extending from an aerodynamically infinite height to a zero height. In the method, (i) the range of heights is subdivided into at least two consecutive sets of heights; (ii) for one of the sets of heights, the variation of said aerodynamic coefficient is determined by wind tunnel tests using a model of the aircraft; and (iii) for the other of the sets of heights, the variation of said aerodynamic coefficient is determined by digital simulation reproducing by computation the physical reality of the air flow around said aircraft.

Abstract: To render secure a connection between an access point of a short-range network and a mobile terminal within a cellular network while precluding acquisition of a PIN code, a platform transmits a confirming message, including a secret code and the access point address retrieved from a terminal request, to the terminal through the cellular network and a connection request message including the secret code and the mobile terminal address to the access point. The access point authenticates the terminal, or the terminals authenticate each other as a function of a session key determined as a function of the secret code retrieved from the connection request message and from the confirming message.

Abstract: The invention relates to a method and device for determining the width of a safety corridor for an aircraft and to a method and system for securing the automatic low-altitude flight of an aircraft. The inventive device (1) comprises: means (3) which can be used by an operator in order to enter a plurality of errors which each have an impact on the automatic low-altitude flight of the aircraft; means (4) for determining an excursion probability of a safety corridor that is not to be crossed; and means (5) for determining the width of said safety corridor form the aforementioned errors and excursion probability, taking account of at least one mathematical expression linking at least the errors, the excursion probability and the width.

Abstract: To render secure a connection between an access point of a short-range network and a mobile terminal within a cellular network while precluding acquisition of a PIN code, a platform transmits a confirming message, including a secret code and the access point address retrieved from a terminal request, to the terminal through the cellular network and a connection request message including the secret code and the mobile terminal address to the access point. The access point authenticates the terminal, or the terminals authenticate each other as a function of a session key determined as a function of the secret code retrieved from the connection request message and from the confirming message.