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scalarTransportFoam erased my original data and has very slowly transport results

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Old   July 16, 2012, 17:10
Default scalarTransportFoam erased my original data and has very slowly transport results
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Roro Wang
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Hi foamers,

I used other solver (e.g. pisoFoam) to generate a series of velocity fields.
Then, I wanted to use scalarTransportFoam to calculate the scalar transport by the given velocity fields.
So I just simply type scalarTransportFoam after setting up BC for T in 0 directory and adding DT in transportProperties, as well as some more corresponding modification in the fvSolution and fvSchemes to make it run.

It runs without error, but my original U data has been replaced by the U file in 0 directory and the transport is actually slow, which looks like the U is not read in at all.

Could anybody help me?

Thanks.

foamWang
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Old   July 17, 2012, 03:23
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Anton Kidess
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Did you start the simulation from latestTime?
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Old   October 30, 2013, 18:20
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Vishal Achasrya
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Hi,

I think starting the simulation from latestTime means that only the U from latestTime is used. But what if for every time-step, I want scalarTransportFoam to use the U from that time-directory that was obtained from a different simulation?
Say I have time-directories 0, 0.1, 0.2 etc all with a U file in them for that time, then can i copy these to scalarTransportFoam and get it to use the U from that time if I set my time-step to 0.1 and startTime to 0? I would have to technically move the code block that reads U, into the time-loop in the solver code. But this should work right?

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Old   October 31, 2013, 03:51
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Hi Vishal

Quote:
I would have to technically move the code block that reads U, into the time-loop in the solver code
That is indeed one option that will work. Note though, that you limited the choice of time step strongly in this case and... it will be rather slow since IO-operations are quite time-demanding.

I would opt to include the scalar transport equation directly into U-field solver and solve the scalar transport on the fly. For 3 reasons:
1. It gives you more flexibility towards choice of time step in the scalar transport.
2. It will go faster than storing all U-field and reading them afterwards
3. You need far less storage space

Cheers,

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