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 new_at_this April 6, 2012 11:09

Implement constant heat flux boundary condition

I have written a matlab code that will solve for the developing temperature field given a velocity field. At the moment I have already implemented the constant wall temperature boundary condition and the results look correct.

Now I am trying to implement the constant heat flux boundary condition. I have the equation below

where T_1 is the first interior point and T_w is the wall temperature.

I convert to non dimensional temp
and calculate the appropriate so that it satisfies the flux and implement it as a dirichlet condition.

When I calculate Nu, defined as

it doesn't ever reach steady state. When it is supposed to reach steady state, the wall temperature increases more slowly than the bulk temperature and I get a decreasing Nu. Anyone seen this type of behavior before or know whats going on? Am I implementing the constant flux boundary condition properly?

 ztdep April 6, 2012 21:46

"and calculate the appropriate so that it satisfies the flux and implement it as a dirichlet condition"
Could you pleaase explain" implement the second kind bc as a first kind".

at the heat flux bc, the boundary condition should like
partial(theta)/partial(n)=?

 new_at_this April 6, 2012 23:35

so by subbing in the equatioin becomes

In my case I have also non dimensionalized y as y*H = y.

I know everything in the above equation except for so I can solve for it and then I implement it as a dirichlet condition.

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