Abstract: Disclosed are techniques for scalar solvers in flow simulations that include simulating using a scalar lattice velocity set in a computing system, movement of scalar particles representing a scalar quantity in a volume of fluid, with the scalar particles carried by flow particles of the volume of fluid, and with the movement of the scalar particles causing collisions among the scalar particles; and evaluating, a non-equilibrium post-collide scalar distribution function of a specified order that is representative of the scalar collision.

Abstract: Techniques for simulating fluid flow on a computer that involve a stable entropy solver are described. The techniques include simulating activity of a fluid across a mesh, the activity of the fluid being simulated so as to model movement of particles across the mesh, storing, in a computer accessible memory, a set of state vectors for each mesh location in the mesh, each of the state vectors comprising a plurality of entries that correspond to particular momentum states of possible momentum states at a corresponding mesh location, simulating a time evolution of entropy of the flow by collecting incoming set of distributions from neighboring mesh locations for the collision operation, calculating by the computer scalar values in each location, determining outgoing distributions as a product of the collision operation and addition of a heat source, and modifying the flow by the computer performing for a time interval, an advection of the particles to subsequent mesh locations.

Abstract: Disclosed are techniques for scalar solvers in flow simulations that include simulating using a scalar lattice velocity set in a computing system, movement of scalar particles representing a scalar quantity in a volume of fluid, with the scalar particles carried by flow particles of the volume of fluid, and with the movement of the scalar particles causing collisions among the scalar particles; and evaluating, a non-equilibrium post-collide scalar distribution function of a specified order that is representative of the scalar collision.

Abstract: Techniques for simulating fluid flow on a computer that involve a stable entropy solver are described. The techniques include simulating activity of a fluid across a mesh, the activity of the fluid being simulated so as to model movement of particles across the mesh, storing, in a computer accessible memory, a set of state vectors for each mesh location in the mesh, each of the state vectors comprising a plurality of entries that correspond to particular momentum states of possible momentum states at a corresponding mesh location, simulating a time evolution of entropy of the flow by collecting incoming set of distributions from neighboring mesh locations for the collision operation, calculating by the computer scalar values in each location, determining outgoing distributions as a product of the collision operation and addition of a heat source, and modifying the flow by the computer performing for a time interval, an advection of the particles to subsequent mesh locations.

Abstract: Techniques for simulating fluid flow using a lattice Boltzmann (LB) approach for solving scalar transport equations and solving for total energy are described. In addition to the lattice Boltzmann functions for fluid flow the techniques include modifying a set of state vectors of the particles by adding specific total energy to states of particles that will be advected and subtracting the specific total energy from states of particles that will not be advected over a time interval and performing advection of the particles according to the modified set of states.

Abstract: A method analyzes physical transport in a proton exchange membrane fuel cell (PEMFC) having three adjacent layers L1, L2, L3, each with a distinct porous structure. A first small scale multiphase simulation S1 of a first portion of the L1/L2 interface is used to characterize the L1/L2 interface. The S1 results are statistically extended to a larger second portion of the L1/L2 interface. The statistically extended L1/L2 interface is used as a boundary condition for a second multiphase simulation S2 to characterize the L2/L3 interface. S1 is repeated using the characterized L2/L3 interface as a boundary condition. S1 and S2 respectively simulate of one or more of momentum, energy, species, and charge transport across the L1/L2 and L2/L3 interface.

Abstract: Described are computer implemented techniques for simulating elements of a fluid flow. These techniques include storing in a memory state vectors for a plurality of voxels, the state vectors comprising a plurality of entries that correspond to particular momentum states of a plurality of possible momentum states at a voxel, storing in a memory a representation of at least one surface that is sized and oriented independently of the size and orientation of the voxels, perform interaction operations on the state vectors, the interaction operations modelling interactions between elements of different momentum states, perform surface interaction operations on the representation of the surface, the surface interaction operations modelling interactions between the surface and substantially all elements of voxels, and performing move operations on the state vectors to reflect movement of elements to new voxels.

Abstract: Disclosed are computer implemented techniques for conducting a fluid simulation of a porous medium. These techniques involve retrieving a representation of a three dimensional porous medium, the representation including pore space corresponding to the porous medium, with the representation including at least one portion of under-resolved pore structure in the porous medium, defining a representative flow model that includes the under-resolved pore structure in the representation, and constructing by the computer system fluid force curves that correspond to fluid forces in the under-resolved pore structure in the representation.

Abstract: Described are computer implemented techniques for simulating elements of a fluid flow. These techniques include storing in a memory state vectors for a plurality of voxels, the state vectors comprising a plurality of entries that correspond to particular momentum states of a plurality of possible momentum states at a voxel, storing in a memory a representation of at least one surface that is sized and oriented independently of the size and orientation of the voxels, perform interaction operations on the state vectors, the interaction operations modelling interactions between elements of different momentum states, perform surface interaction operations on the representation of the surface, the surface interaction operations modelling interactions between the surface and substantially all elements of voxels, and performing move operations on the state vectors to reflect movement of elements to new voxels.

Abstract: Computer implemented techniques for simulating a fluid flow about a surface of a solid, include receiving a coordinate system for representation of a curvilinear mesh that conforms to the surface of the solid, simulating, with a lattice velocity set transport of particles in a volume of fluid, with the transport causing collision among the particles, executing a distribution function for transport of the particles, with the distribution function including a particle collision determination and a change in particle distribution associated with the curvilinear mesh, performing by the computing system, advection operations in the coordinate system under constraints applied to particle momentum values and mapping by the computer system values resulting from simulating onto the curvilinear mesh by translation of the particle momentum values and spatial coordinates determined in the coordinate system into momentum and spatial values in the curvilinear space.

Abstract: Computer implemented techniques for simulating a fluid flow about a surface of a solid are disclosed. These techniques involve receiving a model of a simulation space including a lattice structure represented as a collection of voxels and a representation of a physical object, with the voxels having appropriate resolutions to account for surfaces of the physical object. The techniques also involve simulating movement of particles in a volume of fluid, with the movement of the particles causing collisions among the particles, identifying faces between two voxels where at least one of the faces violates a stability condition, computing a modified flux using a spatially averaged gradient in the vicinity of the two voxels where the at least one of the faces violates the stability condition, and performing by the computing system, advection operations on the particles to subsequent voxels.

Abstract: Computer implemented techniques for simulating a fluid flow about a surface of a solid, include receiving a coordinate system for representation of a curvilinear mesh that conforms to the surface of the solid, simulating, with a lattice velocity set transport of particles in a volume of fluid, with the transport causing collision among the particles, executing a distribution function for transport of the particles, with the distribution function including a particle collision determination and a change in particle distribution associated with the curvilinear mesh, performing by the computing system, advection operations in the coordinate system under constraints applied to particle momentum values and mapping by the computer system values resulting from simulating onto the curvilinear mesh by translation of the particle momentum values and spatial coordinates determined in the coordinate system into momentum and spatial values in the curvilinear space.

Abstract: Computer implemented techniques for simulating a fluid flow about a surface of a solid, include receiving a coordinate system for representation of a curvilinear mesh that conforms to the surface of the solid, simulating, with a lattice velocity set transport of particles in a volume of fluid, with the transport causing collision among the particles, executing a distribution function for transport of the particles, with the distribution function including a particle collision determination and a change in particle distribution associated with the curvilinear mesh, performing by the computing system, advection operations in the coordinate system under constraints applied to particle momentum values and mapping by the computer system values resulting from simulating onto the curvilinear mesh by translation of the particle momentum values and spatial coordinates determined in the coordinate system into momentum and spatial values in the curvilinear space.

Abstract: Techniques for simulating fluid flow using a lattice Boltzmann (LB) approach for solving scalar transport equations and solving for total energy are described. In addition to the lattice Boltzmann functions for fluid flow the techniques include modifying a set of state vectors of the particles by adding specific total energy to states of particles that will be advected and subtracting the specific total energy from states of particles that will not be advected over a time interval and performing advection of the particles according to the modified set of states.

Abstract: Disclosed are computer implemented techniques for conducting a fluid simulation of a porous medium. These techniques involve retrieving a representation of a three dimensional porous medium, the representation including pore space corresponding to the porous medium, with the representation including at least one portion of under-resolved pore structure in the porous medium, defining a representative flow model that includes the under-resolved pore structure in the representation, and constructing by the computer system fluid force curves that correspond to fluid forces in the under-resolved pore structure in the representation.

Abstract: Techniques for simulating fluid flow using a lattice Boltzmann (LB) approach for solving scalar transport equations and solving for total energy are described. In addition to the lattice Boltzmann functions for fluid flow the techniques include modifying a set of state vectors of the particles by adding specific total energy to states of particles that will be advected and subtracting the specific total energy from states of particles that will not be advected over a time interval and performing advection of the particles according to the modified set of states.

Abstract: Described are computer implemented techniques for simulating elements of a fluid flow. These techniques include storing in a memory state vectors for a plurality of voxels, the state vectors comprising a plurality of entries that correspond to particular momentum states of a plurality of possible momentum states at a voxel, storing in a memory a representation of at least one surface that is sized and oriented independently of the size and orientation of the voxels, perform interaction operations on the state vectors, the interaction operations modelling interactions between elements of different momentum states, perform surface interaction operations on the representation of the surface, the surface interaction operations modelling interactions between the surface and substantially all elements of voxels, and performing move operations on the state vectors to reflect movement of elements to new voxels.

Abstract: A method comprising: simulating, in a lattice velocity set, movement of particles in a volume of fluid, with the movement causing collision among the particles; based on the simulated movement, determining relative particle velocity of a particle at a particular location within the volume, with the relative particle velocity being a difference between (i) an absolute velocity of the particle at the particular location within the volume and measured under zero flow of the volume, and (ii) a mean velocity of one or more of the particles at the particular location within the volume; and determining, based on the relative particle velocity, a non-equilibrium post-collide distribution function of a specified order that is representative of the collision.

Abstract: Disclosed are techniques for performing a flow simulation that include storing in a memory state vectors for a plurality of voxels, the state vectors comprising a plurality of entries that correspond to particular momentum states of a plurality of possible momentum states at a voxel. The techniques also include storing in a memory a representation of at least one surface and performing interaction operations on the state vectors, the interaction operations modelling interactions between elements of different momentum states. The techniques also include performing surface interaction operations which model interactions between the surface and elements of at least one voxel near the surface, including modeling a wall shear stress direction that is not parallel to a flow velocity direction and performing move operations on the state vectors to reflect movement of elements to new voxels.

Abstract: This description relates to computer simulation of physical processes, such as computer simulation of multi-species flow through porous media including the determination/estimation of relative permeabilities for the multi-species flow through the porous media.