Not isotropic phenomenon during natural convection process
 

Hello everyone,

I use my app based on MOOSE to simulate the transient natural convection process in 3D faulted geothermal field (only involving thermal and hydraulic coupling process) recently. All materials, initial conditions (thermal gradient:0.03 K/m; hydraulic gradient:9.81e+3 Pa/m) and boundary conditions (Ptop=1e+5 Pa; Ttop= 293.15 K; heat flux at bottom= 0.12 W/m2) are isotropic. However, during the simulation process, some anisotropic phenomena occur (figure1) and finally, there is an isotropic phenomenon (figure2).

In addition, I use SUPG (SUPG Parameters: effective length: average; coefficient: transient brooks) to decrease the high Peclet number in fault block. However, the simulation will be break if I turn off the SUPG. I think the anisotropic phenomena could be related to the SUPG method.
My question is whether this phenomenon is correct? Should during all the natural convection process the temperature and velocity distribution scheme be isotropic?

Could you please give me some suggestions on that? Thanks a lot.


Yan