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February 14, 2005, 05:35 |
different mass flow rates
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#1 |
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hi anybody! I have problem with calculating the mass flow rate. I used the Turbo postprocessing panel for calculation mass flow rate (oultet) boundary. I was suprised when I calculated the mass flow rate using 'report-> surface integrals'. Calculated mass flow rate:
Density(average)*Velocity(radial,average)*Area =mass flow rate. Obtained mass flow rate using area- and mass-weighted average report types gave different m.f.rates than one calculated by turbo post. panel. Is my formulation of m.f.rate wrong, or just turbo post. panel has some bugs. Please help, I don't know which value is correct. |
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February 14, 2005, 13:48 |
Re: different mass flow rates
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#2 |
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Hi Micheal,
You should not average the values first. Rather, calculate the sum of Density*Velocity_normal*Area_normal. Fluent should have a function to calculate Mass Flow's directly, since the IP mass flows will differ slightly from this calculation. -Robin |
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February 15, 2005, 04:24 |
Re: different mass flow rates
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#3 |
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Thanks a lot Robin. You have right. I have one question more: My problem is unsteady, so I would like to save mass flow rates through the inlet and outlet boundaries every time step. It is easy to save some quantities using
solve->monitors->surface-> and so on… But there is no possibility to monitor mass flow rate through the selected zone. Is there any easy possibility to do that without writing UDF (unfortunately T am not so familiar in UDFs)? best regards |
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February 15, 2005, 21:47 |
Re: different mass flow rates
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#4 |
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I haven't the foggiest idea of how to do this in Fluent. I can tell you the expression for CFX-5, but that isn't going to help you much.
Regards, Robin |
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February 21, 2005, 04:48 |
Re: different mass flow rates
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#5 |
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I think that you just need to use a Custom Field Function, not a UDF.
Regards George |
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