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Old   March 29, 2004, 08:27
Default strange phenominon
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dan
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I have done one analysis in which rho, mu and Cp are temperature dependant. Oil is flowing through a closes channel and heat flux is applied at channel's walls. The temperature rises as oil passes through it. The area of the channel varies. If I plot temp vs length plot of the oil. It is non linear and has high temperature at location where velocity is low. But at exit velocity suddenly reduces, and to my surprise temperature also suddenly drops. How this is happening? My model contains RFR (channel is rotating). I have extended boundaries at inlet and exit. Kindly guide.

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Old   March 29, 2004, 23:45
Default Re: strange phenominon
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p
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Check:

a) formulation and discretisation of the continuity eqn., momentum eqns., energy eqn.

b) kind of discretisation for convective terms (first/second order)

If your own code, why not take up sort of validation cases at each step - constant rho, mu, cp, cross sec area of chaneel, etc. Then introduce variation of rho, then mu, then cp, then channel area. I hope heat flux is constant, otherwise take care of that also.

My guess at this stage is that there is some problem with the continuity eqn.
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