Lattice Units Conversion
In most lattice Boltzmann simulations is the basic unit for lattice spacing, so if the domain of length has lattice units along its entire length, the space unit is simply defined as . Speeds in lattice Boltzmann simulations are typically given in terms of the speed of sound. The discrete time unit can therefore be given as, where the denominator is the physical speed of sound.
For small-scale flows (such as those seen in porous media mechanics), operating with the true speed of sound can lead to unacceptably short time steps. It is therefore common to raise the lattice Mach number to something much larger than the real Mach number, and compensating for this by raising the viscosity as well in order to preserve the Reynolds number.
Read more about this topic: Lattice Boltzmann Methods
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