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December 10, 2009, 20:58 
A simple problem with mfix

#1 
New Member
ZRR
Join Date: Apr 2009
Posts: 9
Rep Power: 8 
Hello:
First of all, thank you for your time. I used the MFIX (the stable one) make a simple test, just like the Fig in the attchments (geometry of vessel and array of numerical grids). It is a 2D problem, there are two mass_inflow BC, one PO BC, for the wall NSW is adopted. One of the MI BC MIA is in the IC, the black area is define as NSW too. But with the same install, TESTA cannot converge, but the TESTB can. I output the profile of velocity, both TESTA and TESTB, the value is different, it clear that TESTA is greater than TESTB, but with a similar tendency . I do not know how to solve it, hope you can help me. Looking forward to your reply! Best regards! PS: The input files MFIX. dat for TESTA is as follows: ! It is made available in MFIX documents ! Runcontrol section RUN_NAME = 'des_fb1' DESCRIPTION = 'fluid bed with single central jet' RUN_TYPE ='NEW' ! 'RESTART_1'! UNITS = 'cgs' TIME = 0.0 !start time TSTOP = 10.0 DT = 5E4 !time step DT_MAX = 1E3 ENERGY_EQ = .FALSE. !do not solve energy eq SPECIES_EQ = .FALSE. .FALSE. !do not solve species eq MOMENTUM_X_EQ(1) = .FALSE. MOMENTUM_Y_EQ(1) = .FALSE. MOMENTUM_Z_EQ(1) = .FALSE. ! DT_FAC = 1.0 MAX_NIT = 250 TOL_RESID = 1.E3 ! Geometry Section COORDINATES = 'cartesian' XLENGTH = 3. !X length IMAX = 3 !cells in i direction YLENGTH = 5. !height JMAX = 5 !cells in j direction NO_K = .TRUE. !2D, no k direction DZ(1) = 0.4d0 !Define DZ to be particle !for 2D DEM cases GRAVITY = 980 ! Gasphase Section MU_g0 = 1.8E4 !constant gas viscosity RO_g0 = 1.205E3 !constant gas density ! Solidsphase Section RO_s = 2.7 !solids density D_p0 = 0.4 !particle diameter e = 0.9 !restitution coefficient Phi = 30.0 !angle of internal friction EP_star = 0.42 !void fraction at minimum ! fluidization ! Initial Conditions Section ! 1. bed IC_X_w(1) = 0.0 !domain IC_X_e(1) = 3.0 ! 0 < x < 15, 0 < y < 30 IC_Y_s(1) = 0.0 IC_Y_n(1) = 5.0 ! initial values in the region IC_EP_g(1) = 1.00 ! void fraction IC_U_g(1) = 0.0 ! xdir gas velocity IC_V_g(1) = 0 ! ydir gas velocity IC_U_s(1,1) = 0.0 IC_V_s(1,1) = 0.0 IC_T_G(1) =273. IC_T_S(1,1)=273 ! Boundary Conditions Section ! 1. Central jet BC_X_w(1) = 1.0 ! central jet BC_X_e(1) = 2.0 ! 7 < x < 8, y = 0 BC_Y_s(1) = 0.0 BC_Y_n(1) = 0.0 BC_TYPE(1) = 'MI' !specified mass inflow BC_EP_g(1) = 1.0 BC_U_g(1) = 0.0 BC_V_g(1) = 0 !inlet jet vel BC_P_g(1) = 0.0 ! 1. Secondary flow 1 BC_X_w(2) = 0.0 BC_X_e(2) = 1.0 BC_Y_s(2) = 0.0 BC_Y_n(2) = 0.0 BC_TYPE(2) = 'MI' !specified mass inflow BC_EP_g(2) = 1.0 BC_U_g(2) = 0.0 BC_V_g(2) = 0.0 BC_P_g(2) = 0.0 ! 1. Secondary flow 2 BC_X_w(3) = 2.0 BC_X_e(3) = 3.0 BC_Y_s(3) = 2.0 BC_Y_n(3) = 2.0 BC_TYPE(3) = 'MI' !specified mass inflow BC_EP_g(3) = 1.0 BC_U_g(3) = 0.0 BC_V_g(3) = 0.0 BC_P_g(3) = 0.0 ! 1. Secondary flow 2 BC_X_w(5) = 2.0 BC_X_e(5) = 3.0 BC_Y_s(5) = 0.0 BC_Y_n(5) = 2.0 BC_TYPE(5) = 'NSW' !specified mass inflow ! 2. Exit BC_X_w(4) = 0.0 ! top exit BC_X_e(4) = 3.0 ! 0 < x < 15, y = 90 BC_Y_s(4) = 5.0 BC_Y_n(4) = 5.0 BC_TYPE(4) = 'PO' !specified pressure outflow BC_P_g(4) = 0.0 ! ! DES INPUT PARTICLES = 1 ! Number of particles MN = 14 ! Maximum number of neighbors allowed per particle KN = 800000 ! Normal interparticle collision spring constant KT = 800000 ! Tangential " " " " ETA_DES_N = 18 ! Normal interparticle damping coefficient ETA_DES_T = 18 ! Tangential " " " MEW = 0.2 ! Interparticle friction coeffienct KN_W = 1200000 ! Normal particlewall collision spring constant KT_W = 1200000 ! Tangential " " " " ETA_N_W = 22 ! Normal particlewall damping coefficient ETA_T_W = 22 ! Tangential " " " MEW_W = 0.1 ! Particlewall friction coefficient DES_NEIGHBOR_SEARCH = 2 ! Particle neighbor search method; 1=nsquare; 2=quadtree; 3=octree NEIGHBOR_SEARCH_N = 1 DTSOLID_FACTOR = 0.1D0 P_TIME = 10.0 ! DES Logicals DISCRETE_ELEMENT = .TRUE. WALLDTSPLIT = .TRUE. DES_CONTINUUM_COUPLED = .TRUE. TSUJI_DRAG = .TRUE. ! End DES Input ! Output Control ! OUT_DT = 0.05 !write text file BUB01.OUT ! every 0.1s RES_DT = 0.01 !write binary restart file ! BUB01.RES every 0.01 s NLOG = 25 !write logfile BUB01.LOG !every 25 time steps FULL_LOG = .TRUE. !display residuals on screen !SPX_DT values determine how often SPx files are written. Here BUB01.SP1, which !contains void fraction (EP_g), is written every 0.01 s, BUB01.SP2, which contains ! gas and solids pressure (P_g, P_star), is written every 0.1 s, and so forth. ! ! EP_g P_g U_g U_s ROP_s T_g X_g ! P_star V_g V_s T_s X_s Theta Scalar ! W_g W_s SPX_DT = 0.01 0.01 0.01 0.1 100. 100. 100. 100.0 100. 100. 100. ! The decomposition in I, J, and K directions for a Distributed Memory Parallel machine NODESI = 1 NODESJ = 1 NODESK = 1 ! Sweep Direction LEQ_SWEEP(1) = 'ISIS' LEQ_SWEEP(2) = 'ISIS' LEQ_SWEEP(3) = 'ISIS' LEQ_SWEEP(4) = 'ISIS' LEQ_SWEEP(5) = 'ISIS' LEQ_SWEEP(6) = 'ISIS' LEQ_SWEEP(7) = 'ISIS' LEQ_SWEEP(8) = 'ISIS' LEQ_SWEEP(9) = 'ISIS' 

December 14, 2009, 20:37 

#2 
New Member
ZRR
Join Date: Apr 2009
Posts: 9
Rep Power: 8 
Is anyting i can do?


October 31, 2013, 05:11 

#3 
Member
mohsen
Join Date: Sep 2013
Posts: 34
Rep Power: 4 
Dear joshzrr
i downloaded the MFIX files from MFIX site, and i read the readme.pdf but i don't know how to use the MFIX code in windows 7 64 bit .Fortran software is installed on my computer. can you help me please to use MFIX code ? Thanks a lot in advance. 

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