Learning Forum

[KarlDD]

Hello,

my questions are dedicated to the definition of a porous zone in ANSYS Fluent (version 2021 R2).
According to the User's Guide, there are two (not equivalent) implementations of a source term:

- default formulation (equation 7.1)

- alternative formulation (equation 7.24 only for inertial term)

Question Q1:
From my understanding, the default formulation is rotationally invariant,
but the alternative formulation is not rotationally invariant due to the specific nonlinearity of the inertial term.
Is that correct?

Question Q2:
Condider a case where the reference frame of the porous zone (defined by direction vectors in Fluent) is rotated to the global coordinate system.
On which frame are the quantities S_i, C_i and v_i of the alternative formulation based?
From the documentation, I cannot clearly see where a transformation of quantities between reference frames is implemented in Fluent.
However, this becomes important if rotational invariance is not fulfilled.

Thanks for your help!

[Prashanth]

Hello,

• if the pressure drop from inertial resistances is across anisotropic medium, the alternative formulation is needed.
• for default formulation, directional velocity is used in the intertial quadratic term; but for alternative formulation, "velocity magnitude" is used in the inertial quadratic term