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: 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: 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: A method includes simulating, in a lattice velocity set, transport of particles in a volume of fluid, with the transport causing collision among the particles; and generating a distribution function for transport of the particles, wherein the distribution function comprises a thermodynamic step and a particle collision step, and wherein the thermodynamic step is substantially independent of and separate from the particle collision step.

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.