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April 25, 2019, 06:22 |
Power and Enthalpy in fvOptions file
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#1 |
Senior Member
Raza Javed
Join Date: Apr 2019
Location: Germany
Posts: 183
Rep Power: 7 |
Hello everyone,
I am trying to generate a heat source using Power of 10W using fvOptions file. So for this, I have given the value of 10 to "h" in fvOptions like below: Code:
heatSource { type scalarSemiImplicitSource; active true; scalarSemiImplicitSourceCoeffs { selectionMode all; // all, cellSet, cellZone, points // cellZone heatSrc; //cellSet c1; volumeMode absolute; // specific; injectionRateSuSp { h (10 0); } } } I have read in this forum that If I need a power of say 10W, then I just need to put that value as "h (10 0)" in fvOptions and the volumeMode should be "absolute". The temperature of my heat source is changing when I check it in paraview but I don't understand that how this power(W) is changing my temperature? What is the mathematical relationship between them? Also some people also say that this 'h' is Enthalpy, so I am confused that if this is enthalpy then how can I put my power directly in "h" ? Also I went through the solver log file to see how solver reads the fvOtption file. And it shows the following: Code:
Adding fvOptions Creating finite volume options from "constant/fvOptions" Selecting finite volume options model type scalarSemiImplicitSource Source: heatSource - selecting all cells - selected 10599 cell(s) with volume 123000 What does this mean? Code:
-selected 10599 cell(s) with volume 123000 This value remains the same even if I change the value of "h" in my fvOptions file. I shall be very thankful if someone can clear my doubts. Thank you |
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April 26, 2019, 11:03 |
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#2 |
Senior Member
Join Date: Sep 2013
Posts: 353
Rep Power: 21 |
> -selected 10599 cell(s) with volume 123000
This simply means, that your fvOptions is applied to 10599 cells which have a combined volume of 123000 m³. Lets assume you have the following equation: This is the equation for heat conduction inside a solid. It is an equation for enthalpy, but can also be formulated with temperature directly. You can add an explicit source term S to this equation: Now this source term describes internal heat generation. Again, please check a fundamentals book in heat transfer for that. Now: scalarSemiImplicitSource has an explicit and implicit part. Code:
h (10 0); I hope this helps |
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Tags |
fvoptions, heat sources, openfoam, power, temperature |
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