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Old   November 19, 2012, 17:48
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Glenn Horrocks
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What is k? What is this equation representing?
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Old   November 19, 2012, 19:36
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i am so sorry that i forgot explain the K. the K in the equation is present electrical conductivity of the flow. the whole equation is the relation of the electrical conductivity with gas volume fraction and temperature of the flow.
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Old   November 20, 2012, 18:34
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Why shouldn't this just be a function of the local volume fraction and temperature? Why does the vf and t of somewhere else affect the value (this happens through the averaging process)?
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Old   November 21, 2012, 07:28
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there is just the experience formula. so i do the simulate to find the effect to the current density.
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Old   November 21, 2012, 19:21
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What do you mean by "there is just the experience formula."?

The electrical conductivity of a control volume should be (in my understanding) a function of the conditions in that control volume only, so:

k=a*gas.vf + b*T

Where gas.vf and T are the local volume fraction and temperature. The solver will then do the current density simulation with a varying conducitivity and will work out all the path effects. This approach is simple to implement.

Is this approach valid? If not valid can you explain why not?
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Old   November 21, 2012, 22:08
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yes, i think it is a valid approach and i had gain the differert current density without a varying conducitivity in the simulation.but as the relation of the conductivity and the gas. VF and temperature had established, i can not know how to do in my simulation. so i can not gain the result.
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Old   November 21, 2012, 22:15
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sorry,ghorrocks, "there is just the experience formula." means that it is j an experience equation. maybe the temperature also effected the gas.VF. so the relation is a multiplication not a addition.
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Old   November 22, 2012, 05:26
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I do not know what you mean by the last comment and I still cannot see you a simple local equation is not suitable.

But I will forget that and just try to implement what you want. You say "k(z)=k0*(1+a*(T(z)-T0)*(1-b(z))),where,k0 and T0 is initialization, and the T(Z) and the b(z) is the temperature function and gas volume fraction function along the z axis respectively.". What function controls k(z), T(z) and b(z)? Is the simulation 1D? Can you post an image of the geometry? And describe the flow?
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Old   November 29, 2012, 04:15
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hi, ghorrocks, i am sorry for the late reply. i try to upload a picture but unsuccessful. the simulation is not 1D but 3D. the T(Z) and K(Z) is just the assumption, actually they are the functions of position. so gaining the T and K at different position is the key for the question. thank you !
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