# Fluid ModelsΒΆ

Fluids are gases and liquids that flow when subject to an applied shear stress. For single-phase fluids, momentum transport is governed by the fluid density and viscosity. For multi-phase systems, the surface tension must also be defined to describe dynamics at the interface between two phases.

M-Star CFD can handle both Newtonian and non-Newtonian fluid rheology. The available fluid models, along with the relevant simulation parameters, are described in the sections that follow.

Laminar and transitional flows are typically modeled via direct numerical simulation. Turbulent fluid flows in M-Star CFD are modeled using implicit large eddy simulations (ILES) or large eddy simulation (LES). Additional theoretical details related to the LES model are provided in the Theory and Implementation section of this manual.

Users must select a fluid configuration. Four configurations are available:

Single phase

Free surface

Two-fluid immiscible

None

In the sections that follow, each of these configurations are discussed in detail.