CFD Online Logo CFD Online URL
Home > Forums > Software User Forums > ANSYS > FLUENT

Porous media convection UDS equations

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   September 19, 2003, 14:38
Default Porous media convection UDS equations
Posts: n/a
Hi All,

I am modeling the convective heat transfer in a heated porous media. The convection is included as a source term (hv*(Ts-Tg)). Thermal non-equilibrium is considered and the solid phase equation is implemented via UDS. I define an additional UDS for local porosity (motivated by Greg Perkins). I am solving for the steady state solid temperature distribution. My question is concerned with the implementation of the steady state UDS equations in Fluent.

The general solid medium energy equation is:

d/dt((1-epsi)*rho_s*c_s*T) = d/dx(KdT/dt) + S

epsi->porosity; Scalar -> h = c_s*T; T-> Solid medium temperature, S -> Source term

From this, in order to get steady state equations, I think that there are 2 ways:

Method 1:

Set the left hand side to zero, we get,

d/dt(KdT/dt) + S = 0 in W/m3

Method 2:

Take out the constants from left hand side,

(1-epsi)*rho_s*c_s*dT/dt = d/dx(KdT/dt) + S

Divide the entire equation by these constants,

dT/dt = d/dx(KdT/dt)/(1-epsi)*rho_s*c_s + S/(1-epsi)*rho_s*c_s in K/s

Now set the left hand side to zero, we get:

d/dx(KdT/dt)/(1-epsi)*rho_s*c_s + S/(1-epsi)*rho_s*c_s = 0

This means that:

my diffusion coefficient is: K/(1-epsi)*rho_s*c_s

and source term is: S/(1-epsi)*rho_s*c_s

I ran the Fluent case using the above-mentioned 2 methods. One would expect the same answer from both the cases. But, that did not happen to me.

Does anybody see any problem in my formulation and implementation in Fluent?

Thanks in advance,

  Reply With Quote

Old   September 19, 2003, 19:53
Default Re: Porous media convection UDS equations
Posts: n/a
Hi All,

There is a small typo in my previous post.

The diffusion term is defined as:

d/dx(KdT/dx) and NOT d/dx(KdT/dt) as posted.


  Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Porous media setup issues in Fluent Bernard Van FLUENT 29 January 26, 2017 04:09
UDS porous media Nagendra FLUENT 11 July 21, 2016 08:03
How to model granular flow through porous media Axius FLUENT 2 August 7, 2014 10:34
UDS for Porous Media cp FLUENT 6 June 26, 2012 13:44
porous media: Fluent or Star-CD? Igor Main CFD Forum 0 December 5, 2002 15:16

All times are GMT -4. The time now is 22:17.