Autodesk Simulation CFD

[#1]

I am running a transient model with the Solar Heating feature, but I need to add convection through light wind.  Since the solar model I am running is transient, should I run the flow model as transient as well?  I have tried to running a steady state flow only model (to establish the external flow field) followed by the transient thermal model, but the radiation doesn't seem to work properly after running the steady state model. Also, I am not sure if adding the transient run to a steady state run follows "best practices"

I just need some guidance and recommendation on how I should approach the addition of steady flow to a transient solar model.

Thanks

[#2]

Hi,

Your approach sounds perfectly sensible, there is nothing wrong with running a transient simulation off the back of a steady state one. We often do this to lock the flow as it is and solve only for thermal.

Please could you be more specific about what happens when you try to run with radiation?

[#3]

Jon,

Thanks for the quick reply. I have gotten the model to work but there is an inconsistant issue with the transient and radiation conditions.  The model has both a piecewise linear temperature profile and the transient solar condition.

When I start the transient simulation I'll notice that the program does not follow through with the Radiation/Resiprosity calculations.  The message window reports that they have started but is lacking the view space error results.  Then, once I let the model run for several hundered iterations it is clear that the transient conditions are not being applied; the  convergance plot for temperature eventually stabilizes to a flat line. I was concerned that the data from previous iterations (ussually this problem would occur when I ran the simulation for additional iterations, or tried to follow the steady state run) was corrupting the model so I have applied the following flags:

ForceReBuildOfRVQFile

rad_heat_flux_freq

Since I first applied the flags the issue has not returned. I will try to provide more specifics if the problem occurs again.

Mike

[#4]

It would be wise to fix the radiation issue first, perhaps you have more mesh than your system allows for the radiation calcualtion? Have you tried running with less mesh or maybe a 1/2 model if possible?