# Porous media

I am doing a simulation on capillary driven evaporator to get its temperature profile, its a porous media so there has to be an effective thermal conductivity. Based on porosity, solid material conductivity and working fluid conductivity fluent is by default taking volume average effective thermal conductivity i.e.,

k_eff=k_s(1-porosity) + porosity(k_l)

but this is over predicting the value so I want to use some other correlation i.e.,

k-eff=k_l(k_l/k_s)^-(1-porosity)^(0.6)

but there is no option to input effective thermal conductivity so if I am making a UDF then how to implement it.

Please help me with the solution I am really struggling with the problem

## Comments

You alter the conductivity in the materials panel. So you could make a new material for the porous zone and work out the correction factor to the solid conductivity which avoids the need for a UDF.

Okay I can consider this thing

Thanks for your suggestion

I am doing simulation for two fluid in which there is requirment of rock properties and main problem is to enter permeability of both fluid so suggest that how can enter this properties in fluent data base .

For Eulerian multiphase you can enter the permeability (resistance) coefficients on a per phase basis. They're set in the cell zone panel as it's a porous property not a flowing material property.

sir actually my problem is that to to see the instability at the interface of oil water interface. when oil is extracted from the sea reserviour is main condition . please tell me the procedure for simulation in ansys fluent . and thank you for previous reply.

You'll need to turn on the multifluid VOF then, and include the Corey models: you're going to struggle to see any instabilities as these tend to be at the micro-scale and we model formations at the bulk scale.

sir actually i am trying in vof model but problem comes at the interface where instability will not occur . I do not recognize the corey model in fluent so if it possible from this model then give the link to understand this model.

Have a look in the documentation: 6.2.3.7.16. Specifying the Relative Permeability in the User's Guide (R19.2).