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zhangxu86铜虫 (小有名气)
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[求助]
曳力函数的的UDF 已有2人参与
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请问各位大侠，我的模型使用的是欧拉模型，物质是沙和水，请问一下，编写沙水两者之间的曳力时，是使用液液交换系数还是使用液体-固体交换系数呢？下面的是我看到一篇流化床立体上的程序，不知道为什么计算两次K和f呢？上面一段程序使用的就是Syamlal-O‘Brien，下面一段就不明白了。。。。。 /* This is a routine for customizing default Syamlal drag law in Fluent 6. The default drag law uses 0.8 (for void<=0.85) and 2.65 (void>0.85) for bfac. This is for a min fluid vel of 25 cm/s. The current drag law has been tuned for a min fluid vel of 8 cm/s and uses 0.28 and 9.07 for these parameters. */ #include "udf.h" #include "sg_mphase.h" # define pi 4.*atan(1.) #define diam2 3.e-4 DEFINE_EXCHANGE_PROPERTY(custom_drag_syam, cell, mix_thread, s_col, f_col) { Thread *thread_g, *thread_s; real x_vel_g, x_vel_s, y_vel_g, y_vel_s, abs_v, slip_x, slip_y, rho_g, rho_s, mu_g, reyp, afac, bfac, void_g, vfac, fdrgs, taup, k_g_s; /* find the threads for the gas (primary) and solids (secondary phases). These phases appear in columns 2 and 1 in the Interphase panel respectively*/ thread_g = THREAD_SUB_THREAD(mix_thread, s_col);/*gas phase*/ thread_s = THREAD_SUB_THREAD(mix_thread, f_col);/* solid phase*/ /* find phase velocities and properties*/ x_vel_g = C_U(cell, thread_g); y_vel_g = C_V(cell, thread_g); x_vel_s = C_U(cell, thread_s); y_vel_s = C_V(cell, thread_s); slip_x = x_vel_g - x_vel_s; slip_y = y_vel_g - y_vel_s; rho_g = C_R(cell, thread_g); rho_s = C_R(cell, thread_s); mu_g = C_MU_L(cell, thread_g); /*compute slip*/ abs_v = sqrt(slip_x*slip_x + slip_y*slip_y); /*compute reynolds number*/ reyp = rho_g*abs_v*diam2/mu_g; /* compute particle relaxation time */ taup = rho_s*diam2*diam2/18./mu_g; void_g = C_VOF(cell, thread_g);/* gas vol frac*/ /*compute drag and return drag coeff, k_g_s*/ afac = pow(void_g,4.14); if(void_g<=0.85) bfac = 0.281632*pow(void_g, 1.28); else bfac = pow(void_g, 9.076960); vfac = 0.5*(afac-0.06*reyp+sqrt(0.0036*reyp*reyp+0.12*reyp*(2.*bfac- afac)+afac*afac)); fdrgs = void_g*(pow((0.63*sqrt(reyp)/vfac+4.8*sqrt(vfac)/vfac),2))/24.0; k_g_s = (1.-void_g)*rho_s*fdrgs/taup; return k_g_s; } DEFINE_EXCHANGE_PROPERTY(custom_drag_ihme, cell, mix_thread, s_col, f_col) { Thread *thread_g, *thread_s; real x_vel_g, x_vel_s, y_vel_g, y_vel_s, abs_v, slip_x, slip_y, rho_g, rho_s, mu_g, reyp, cd, eg, void_g, k_g_s; /* find the threads for the gas (primary) and solids (secondary phases). These phases appear in columns 2 and 1 in the Interphase panel respectively*/ thread_g = THREAD_SUB_THREAD(mix_thread, s_col);/*gas phase*/ thread_s = THREAD_SUB_THREAD(mix_thread, f_col);/* solid phase*/ /* find phase velocities and properties*/ x_vel_g = C_U(cell, thread_g); y_vel_g = C_V(cell, thread_g); x_vel_s = C_U(cell, thread_s); y_vel_s = C_V(cell, thread_s); slip_x = x_vel_g - x_vel_s; slip_y = y_vel_g - y_vel_s; rho_g = C_R(cell, thread_g); rho_s = C_R(cell, thread_s); mu_g = C_MU_L(cell, thread_g); /*compute slip*/ abs_v = sqrt(slip_x*slip_x + slip_y*slip_y); /*compute reynolds number*/ reyp = rho_g*abs_v*diam2/mu_g; cd = (24./(reyp+SMALL)) + 5.48*pow((reyp+SMALL),-0.573) + 0.36; void_g = C_VOF(cell, thread_g);/* gas vol frac*/ eg = pow(void_g,-2.65); k_g_s = (3./4.)*(cd*(1.-void_g)*abs_v*rho_g*eg)/diam2; return k_g_s; } |
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zhangxu86
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5楼2011-10-26 19:30:10
2楼2011-10-25 22:52:01
zhangxu86
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3楼2011-10-26 09:12:50
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