Force darcy fluid flow component to zero

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Force darcy fluid flow component to zero

kmh435
Hello,
I'm working on a 3D Darcy fluid flow model with hydraulic gradients in the x and the z. I have a lower permeability subdomain within another subdomain.
Unexpectedly, there is a small component of flow in the y-direction near the interior boundary of the subdomain, probably due to the difference in permeability. I’d like to set this zero in case it affects the thermal properties I’m considering. Is there a simple approach by editing the Darcy equation? Or another approach? I’ve tried deleting the py_y variable from the equation to no effect.
Basically (-kap_dl/eta_dl*py) needs to be set to zero for the duration of simulation.
Thanks!
kevin
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Re: Force darcy fluid flow component to zero

Precise Simulation
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kmh435 wrote
Hello,
I'm working on a 3D Darcy fluid flow model with hydraulic gradients in the x and the z. I have a lower permeability subdomain within another subdomain.
Unexpectedly, there is a small component of flow in the y-direction near the interior boundary of the subdomain, probably due to the difference in permeability. I’d like to set this zero in case it affects the thermal properties I’m considering. Is there a simple approach by editing the Darcy equation? Or another approach? I’ve tried deleting the py_y variable from the equation to no effect.
Basically (-kap_dl/eta_dl*py) needs to be set to zero for the duration of simulation.
Thanks!
kevin
Hi Kevin,

There is no standard way to enforce or fix a gradient pointwise in domains, as you've noticed omitting "py_y" does not enforce a constraint (the variable/gradient can still be influenced by boundary conditions and other variables). The best to proceed depends a little on the end goal, if its possible to attach a model or script file I might be able to give better suggestions.
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Re: Force darcy fluid flow component to zero

kmh435
Thank you very much for your response.
Just to clarify, there's no way to set the permeability and viscosity to zero in the y-direction either? While retaining hydraulic properties as a function of x and z of course.
 I won't push it any further by using scripts if it cannot be done within the GUI.
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Re: Force darcy fluid flow component to zero

Precise Simulation
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kmh435 wrote
Thank you very much for your response.
Just to clarify, there's no way to set the permeability and viscosity to zero in the y-direction either? While retaining hydraulic properties as a function of x and z of course.
Yes, you can redefine the permeability, viscosity, and equation to something like

dts_dl*p' - (kap_x/eta_x*px_x + kap_y/eta_y*py_y + kap_z/eta_z*pz_z) = F_dl

and assigning "kap_x_i/eta_x_i" using the coefficients dialog box. However setting "kap_y = 0" would be equivalent to removing the term altogether (which you already tried).