# Problem with fluidized bed simulation using TwoPhaseEulerFoam

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 June 11, 2008, 05:08 Dear FOAMers, I try to get #1 New Member   Matthias Schreiber Join Date: Mar 2009 Location: Cottbus, Germany Posts: 4 Rep Power: 10 Dear FOAMers, I try to get familiar with the twoPhaseEulerFoam-Solver in order to do bubbling fluidized bed simulations in the future. Therefore I started with the tutorial "bed2", but ran into various problems: a) After some timesteps alpha becomes larger than the setting for alpha_max, finally leading to a blown-up alpha-equation. Last output: DILUPBiCG: Solving for alpha, Initial residual = 0.00204016, Final residual = 6.59748e-11, No Iterations 4 Dispersed phase volume fraction = 0.275033 Min(alpha) = -3.08343e-18 Max(alpha) = 0.854645 DILUPBiCG: Solving for alpha, Initial residual = 9.44561e-05, Final residual = 3.20813e-12, No Iterations 4 Dispersed phase volume fraction = 0.275033 Min(alpha) = -3.08222e-18 Max(alpha) = 0.854609 GAMG: Solving for p, Initial residual = 0.00263152, Final residual = 6.91613e-09, No Iterations 27 time step continuity errors : sum local = 2.04471e-09, global = 2.39621e-10, cumulative = 3.95656e-07 DILUPBiCG: Solving for alpha, Initial residual = 0.00101853, Final residual = 5.98548e-11, No Iterations 4 Dispersed phase volume fraction = 0.275033 Min(alpha) = -3.08317e-18 Max(alpha) = 0.854606 DILUPBiCG: Solving for alpha, Initial residual = 8.03968e-05, Final residual = 3.01421e-11, No Iterations 167 Dispersed phase volume fraction = -5.04093 Min(alpha) = -25360.6 Max(alpha) = 8585.28 1 additional process aborted (not shown) b) The bed expansion is not uniform and looks like a funnel. Picture: c) There are "fallen vortices" of high theta values on the side walls of the freeboard. Picture: Does anybody has some hints or best-practice guidelines for this kind of simulation with OF? Many Thanks in advance. Matthias

 June 11, 2008, 11:28 Servus Matthias, there are #2 Member     Andreas Dietz Join Date: Mar 2009 Location: Munich Posts: 79 Rep Power: 10 Servus Matthias, there are several threads about twoPhaseEulerFoam. http://www.cfd-online.com/OpenFOAM_D...es/1/6470.html http://www.cfd-online.com/OpenFOAM_D...es/1/1019.html First one is quite general about the parameters in this solver Second one is more about the issue of convergence problems regarding overpacking. Regards, Andreas

 June 11, 2008, 11:44 Hello Andreas, before posti #3 New Member   Matthias Schreiber Join Date: Mar 2009 Location: Cottbus, Germany Posts: 4 Rep Power: 10 Hello Andreas, before posting I searched for related threads and also consulted the ones you mentioned already. Unfortunately I still have problems to set up a converging simulation. Regards, Matthias

 June 11, 2008, 12:49 Hello Matthias, tomorrow I #4 Member     Andreas Dietz Join Date: Mar 2009 Location: Munich Posts: 79 Rep Power: 10 Hello Matthias, tomorrow I could send you one of my cases if you are then still intersted in them and provide me your email.

 June 12, 2008, 03:37 Hello Andreas, this would b #5 New Member   Matthias Schreiber Join Date: Mar 2009 Location: Cottbus, Germany Posts: 4 Rep Power: 10 Hello Andreas, this would be very nice. Please use this email address: matthias.schreiber_at_tu-cottbus.de Thanks a lot! Matthias

 June 12, 2008, 06:49 Unfortunately Andreas' case wa #6 New Member   Matthias Schreiber Join Date: Mar 2009 Location: Cottbus, Germany Posts: 4 Rep Power: 10 Unfortunately Andreas' case was a bubble column and no fluidzed bed simulation. So, are there some FOAMers with experience in using kinetic theory for gas-solid fluidzed beds? Regards, Matthias

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