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<p>Hi!</p>
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<p>I am simulating a flow where thermodynamic processes takes place.</p>
<p>Since these thermodynamic processes are rather complicated I decided that developing the set up is best done in dimensionfull variables. Here I ran into unexpected problems since it seems as if the parameters in the .rea file do not work as I thought they
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<p>The temperature solution works well. Putting in the "rhocp" and "conduct" of my fluid into "p007" and "p008" gives the results that I expect.</p>
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<p>However, I also have two passive scalars. For them I am not sure what the meaning of "rhocp" actually is.</p>
<p>From eqn (1.4) of Ref. [*] I would assume that setting up a passive scalar \phi with diffusivity a = 2.14E-5 m^2/s evolving as<br>
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<p>D \phi /D t = a Laplacian(\phi) [D/Dt = total derivative]<br>
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<p>means using "rhocp = 1" and "a = 2.14E-5". However, this seems to not be the case, since under these assumptions the corresponding dimensionless set-up gives totally different results.</p>
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<p>If my understanding was correct it would only be the ratio of "rhocp" and "conduct" that matters fo a scalar, but I have found that the individual values matter.</p>
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<p>This leads me to the questions:</p>
<p>* What is the meaning of "rhocp" and "conduct" for a scalar?</p>
<p>* In which dimensions "rhocp" and "conduct" for a scalar?<br>
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<p>* Why does the individual values of "rhocp" and "conduct" matter, when they should no according to eqn (1.4) of Ref. [*]?</p>
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<p>Best,</p>
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<p>Johan<br>
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<p>[*]: User Documentation: <a href="http://nek5000.github.io/NekDoc/Nek_users.pdf" id="LPlnk887259" title="Ctrl+Click or tap to follow the link">
http://nek5000.github.io/NekDoc/Nek_users.pdf</a><br>
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