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Old   October 4, 2005, 18:33
Default moving grid_temperature equation
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George
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Hi all! I am solving the 2D unsteady turbulent Navier-Stokes equation with finite volume and implicit temporal discretisation in a piston-cylinder assembly. Every equation is going fine, except for the temperature one (I solve this instead of the energy equation). When I arrive at the algebraic equation: Ap*Tp=SUM(Ai*Ti)+Su ,the Su sometimes it takes negative values near the piston. I checked also the Ai coefficients and they are OK. Sp is also always negative. As a result everywhere the temperature is around 4 Kelvin, instead of around 350 that it should be. Any help will be much appreciated. Thank you for reading my problem
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Old   October 6, 2005, 12:54
Default Re: moving grid_temperature equation
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russo
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Probably using Artificial viscosity and Inertial Relaxation will help. Read in HELP Fluids Analyses Guide/Flotran Compressible Analyses/Solution Strategies. Also check what specific heat do you apply for the analyses.
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Old   October 6, 2005, 19:39
Default Re: moving grid_temperature equation
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George
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Thank you for your response. I use constant specific heat, because I assume that the temperature will not change very much. The initial is 300 kelvin and the walls are at constant temperature of 350 kelvin. I do not understand where do I find this link: HELP Fluids Analyses Guide/Flotran Compressible Analyses/Solution Strategies. I use the hybrid scheme and the source (Su)is: dP/dt+u*dP/dx+v*dP/dy+den(old)*Temp(old)*Vol(old)/dt.
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