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guoli8832700新蟲 (初入文壇)
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[求助]
求各位fluent大神,UDF曳力問題,幫幫忙,感激不盡。。。 已有1人參與
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書上看到的一個(gè)流化床模擬,代碼我能看懂,但是為什么要用兩個(gè)氣固交換系數(shù),書上是氣相選擇的custom_drag_syam,固相選擇custom_drag_ihme。還有一個(gè)問題,第一個(gè)用的是syamlal-o’brien模型,但是第二個(gè)我查了下,不是常用的幾個(gè)模型啊,沒搞懂,書上也沒說。大神幫忙看下,非常感謝。。。。 其中UDF代碼如下: /* 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; } |
木蟲 (小有名氣)
新蟲 (初入文壇)
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