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September 9, 2011, 21:52 
dpmDEFINE_DPM_LAW

#1 
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hi，
I would like to simulate particle heating in the plasma torch，The total heat ﬂux on the particle surface in the plasma Q is described using the heat transfer attributable to the plasma ﬂow and the radiation loss as Q=*(dp)^2*h*(TTP)((TP)^4(Ta)^4) h is the heat transfer coefﬁcient T is plasma temperature ,TP is particle temperature,epsilonis the emissivity,sigma is Stefan–Boltzmann con stant,Ta is the ambient temperature.dp is particle diameter Q can also be written for the particle temperature change and the phase changes such as melting Q=/6*(*cp*(dp)^3*dTP/dt(tp<Tm,Tm<TP<Tb)................................ .........(1) cp is speciﬁc heat,Tm is melting point ,Tb is boiling point Q=/6*(*Hm*(dp)^3*dx/dt(tp=Tm)......................................... ....................(2) Hm is the latent heat,rho is particle mass Once the particle is completely molten (x = 1), its temperature is allowed to follow again Eq 1 My question is: I'm using UDFs to define the the heat of fusion during the transition,if I use DPM in fluent ,how can i use DEFINE_DPM_LAW Macro to discribe this Eq , Thx 

September 12, 2011, 07:28 

#2 
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UDF that uses DEFINE_DPM_SWITCH to
switch between DPM laws using a criterion. The UDF switches to DPM_LAW_USER_1 which refers to condenshumidlaw since only one user law has been defined.if i have two ,Any suggestions of how to tackle this issue? tomas Last edited by tomas; September 14, 2011 at 09:04. 

September 13, 2011, 06:46 

#3 
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nobody help me！！！！！！！！！


October 5, 2011, 11:31 

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#include "udf.h"
#include "dpm.h" #include "mem.h" #define Ta 300 #define Em 0.8 #define Tm 1983 #define sgb 0.0000000567 #define Tb 2500 #define Cpp 800 #define Hm 369000 #define Hv 12480000 DEFINE_DPM_LAW(HeatLaw,p,ci) { real area, rel_vel, Re, Pr, HTC, delta_temp,delta_x,delta_p; float x = 0; cphase_state_t *c = &(p>cphase); area = 4.0 * M_PI * pow(P_DIAM(p),2.0); Pr = c>sHeat * c>mu / c>tCond;/* Prandtl number */ HTC =c>tCond * (2.0 + 0.6*pow(p>Re,0.5)*pow(Pr,1./3.))/ P_DIAM(p); if (P_T(p) < Tm) { delta_temp = P_DT(p) * (area * HTC * (c>tempP_T(p))area*Em*sgb*(pow(P_T(p),4.0)pow(Ta,4.0))) /(P_MASS(p)*Cpp); P_T(p) = P_T(p) + delta_temp; } else if (P_T(p) = Tm && x>O&& 1>x ) { delta_x=P_DT(p) *6* (area * HTC * (c>tempP_T(p))area*Em*sgb*(pow(P_T(p),4.0)pow(Ta,4.0)))/(P_RHO(p)*Hm); x=x + delta_x; } else if((P_T(p) < Tb )&&(P_T(p) >Tm )) { delta_temp = P_DT(p) * (area * HTC * (c>tempP_T(p))area*Em*sgb*(pow(P_T(p),4.0)pow(Ta,4.0))) /(P_MASS(p)*Cpp); P_T(p) = P_T(p) + delta_temp; x=1; } else { P_T(p)=Tb; delta_p=P_DT(p) *2* (area * HTC * (c>tempP_T(p))area*Em*sgb*(pow(P_T(p),4.0)pow(Ta,4.0)))/(P_RHO(p)*Hv); P_DIAM(p)= P_DIAM(p)+delta_p; } } 

October 5, 2011, 11:39 

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why it showed no change in melting process （Tp=tm ）


November 21, 2011, 09:11 

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.................


November 21, 2011, 09:47 

#7 
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Daniele
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Sorry I can't help you but can you check this?
else if (P_T(p) = Tm && x>O&& 1>x ) 

November 25, 2011, 20:49 

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hank you very much ghost82. I do apprecaite your concern. All the best,
Tomas 

August 29, 2013, 05:20 
DPM in combination with plasma

#9 
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Ian Maes
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Hej Tomas!
This thread is already more than 2 years old and unfortunately I cannot help you with your problem (if that would still be necessary...), but I am trying to model plasma gasification using the DPM model. I read that you also combine a plasma flow with the DPM model, so I was hoping you could help me with something. I have written several UDFs to calculate the hightemperature thermodynamic and transport properties of the plasma flow, but now I find that this results in a conflict with using the DPM model... As far as I know, it's not possible to use a UDF for density, but only the idealgaslaw when using combusting paricles. Did you manage to solve this problem in some way? Thank you in advance! Ian 

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