23.4.8 Granular Temperature

The viscosities need the specification of the granular temperature for the solids phase. Here we use an algebraic equation derived from the transport equation by neglecting convection and diffusion and takes the form [ 364]

 (23.4-22)

 where = the generation of energy by the solid stress tensor = the collisional dissipation of energy = the energy exchange between the fluid or solid phase and the solid phase

The collisional dissipation of energy, , represents the rate of energy dissipation within the solids phase due to collisions between particles. This term is represented by the expression derived by Lun et al. [ 222]

 (23.4-23)

The transfer of the kinetic energy of random fluctuations in particle velocity from the solids phase to the fluid or solid phase is represented by  [ 121]:

 (23.4-24)

FLUENT allows you to solve for the granular temperature with the following options:

• algebraic formulation (the default)

This is obtained by neglecting convection and diffusion in the transport equation (Equation  23.4-22) [ 364].

• constant granular temperature

This is useful in very dense situations where the random fluctuations are small.

• UDF for granular temperature

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Up: 23.4 Mixture Model Theory
Next: 23.4.9 Solids Pressure