Laplacian or time derivative solver

[barnburnr]

To whom is gracious enough to reply,

I am brand new to Elmer so sorry for the newbie question. I want to solve a problem which couples the heat equation with the Poisson equation. In order to couple (one way), I need the Laplacian of the computed heat field as the RHS of my Poisson equation. Alternately, I could use the time derivative of heat as the RHS of my Poisson equation, whichever is easier. From reading through some of the Elmer documentation, I am guessing that I can take the divergence of the flux of the result from the heat solver and use that as a body force in the Poisson-Boltzman solver. Or, perhaps, I should write my own auxiliary solver. What is the easiest way to accomplish this?

Thanks in advance.

Kevin

[raback]

Hi Kevin

I would perhaps rather choose the time derivative of temperature if you have the option to choose. Taking the Laplacian of a field takes more effort. There is a generic keyword "Calculate Velocity" that will give you the time derivative of any transient field to the field "varname Velocity". You could then have the "Charge Density" of PB solver depend on that using some dependecy, for example

Code: Select all

Charge Density = Variable "Temperature Velocity"
  Real MATC "1.23*tx"

-Peter

[barnburnr]

Thanks, Peter! I will give your suggestion a try.

Kevin