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Old   February 7, 2002, 13:33
Default Velocities and masstransfer
  #1
Roustam
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The mixture component is not reacting, it is inert. How can I activate it's transport without energy equation and combustion activating in VR Editor of PHOENICS 3.3. How to activate solution for C1? How to set solv(……) and store(……) in VR Editor to receive solution for velocities first and use these fields to solve concentration transport after? Where do I set a diffusivity coefficient in VR Editor?

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Old   February 12, 2002, 14:08
Default Re: Velocities and masstransfer
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David Glynn
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It's easy!

Look in the "models" submenu of the menu, click "solution control / extra variables", then type the variable name (up to 4 chars) in the Solve or Store box as the case may be.

To solve for velocities, then add a concentration later, first run your case without the concentratrion solved (though it is helpful to have it stored, so that the storage is already allocated when you come to add it later).

Then do a restart run. In the "solution control / extra variables" dialogue box, in the column(s) beneatht the variable(s) you now want to solve (but previously were only stored), click where it says N (for no) in the second row (labelled SOLUTN 2 SOLV). It should change to Y (for yes).

If the scalar is not going to change the velocities, you could do the reverse for them (i.e. change the Y to N under SOLUTN 2 SOLV), i.e. store and not solve them - this will make the run quicker. Note there may be 1 or 2 additional things to do if you want to do this, which I would need to check up on. But in principle you can certainly do this.

In the initialisation submenu, you need to click "restart all variables" to do the restart.

I hope this is helpful!

Good luck,

David Glynn
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Old   February 13, 2002, 14:06
Default Re: Velocities and masstransfer
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Roustam
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Thank you very much! It works! There is only one thing there which is not clear. Scalar transfer should depend also on transport coefficient, e.g. molecular diffusivity. So how can I set the diffusivity, like setting conductivity when I am modeling heat transfer? Thank you.
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Old   February 18, 2002, 13:54
Default Re: Velocities and masstransfer
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David Glynn
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It's easy!

In Phoenics, diffusivities are specified by setting a Prandtl (Schmidt) number, relative to the specified viscosity.

You will find the settings for the Prandtl number (for each variable) at the bottom of the "sub-dialogue box" obtained by clicking the button labelled PIL next to "Advanced Settings" in the "Properties" sub-menu.

These relate to laminar flow (whichj I guess is what you mean, since you mention molecular diffusivities). If the flow is turbulent, Phoenics uses "turbulent Prandtl numbers" to relate the effective turbulent diffusivity to the effective turbulent viscosity (i.e. ENUT). These are to be found in a quite different place! Click on "Settings" next to the turbulence models button in the "Models" submenu.

I hope this makes sense!

Best regards,

David Glynn (Flowsolve)
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Old   February 18, 2002, 14:27
Default Re: Velocities and masstransfer
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Roustam
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Dear David Glynn, Thank you! It works!
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