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Energy balance in conjugative/ porous simulation; Domain Energy is greater than Input

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Old   November 29, 2017, 18:18
Default Energy balance in conjugative/ porous simulation; Domain Energy is greater than Input
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Hello people,

As a result from another thread I use massFlowInt(Total Enthalpy)@Inlet and massFlowInt(Total Enthalpy)@outlet in order to measure Total Energy passing through Inlet and outlet surface areas. I have a fluid-- Porous--fluid, domain in the sequental order with squrare cross section. I performed a transient simulation of Total time = 5hr. I used volumeInt(density*Static Enthaly)@domain to calculate the Energy after simulation. I found the energy(in J) in porous is greater than the accumulated sum of Energy through inlet face considering losses.

So, I tried the same setup and checked the values after Iteration 1 and the energy in Porous is greater than the Energy at Inlet. Is it over predicts? The conditions were 1 kg/s @ Inlet at 500 deg C; "0" Pa releative pressure @ outlet. Transient simulation with time step = 20sec, Total time = 5 hr(900 Iterations in total), I stopped at Iteration 1 and checked the Energy values at Porous using volumeInt(density*Enthalpy) which was higher than the Energy through the Inlet face.
The values are given below:
massFlowInt(Total Enthalpy)@Inlet = 266166 W. so, (time step)20sec*massFlowInt(Total Enthalpy)@Inlet = 31933920 J; volumeInt(density*Static Enthalpy)@Porous = 94102500 J. Am I using wrong formulas? I even tried subtracting the Energy that might be present at the Initialization temp 25 C but even then Porous Energy was way higher than Energy supplied through Inlet. Any setup tweaks necessary? I tried with both fluid and solid densities in the expression volumeInt(density*Static Enthalpy)@domain but still it is way higher.. Suggestions are highly appreciated?
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Old   December 4, 2017, 17:25
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How are you accounting for the porosity in your formulas?

I would check the case for Volume Porosity = 1 first and see if the problem persists. If it does not, then you know you are missing the porosity contribution to the integrals somewhere.
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cfx, energy balance, porous heat transfer, thermal energy

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