[ljp]

Hi,

I'm confused about setting up the custom laws at the "set particle injection" panel, could anyone please clarify that for me?

I need to use the Fluent built-in inert-heating law and the vaporization law, and I wrote another user-defined law to change particle's diameter when certain conditions are met. I also wrote a dpm-switch udf. My question are:

1. About hooking the laws at the custom law panel: should I select inert-heating as the first law, vaporization as the 2nd law, and my user-law as 3rd law, then hook my dpm-switch; or, should I select my user-law as the first law, and make other entries (from 2nd law to 7th law) inactive?

2. About the dpm-switch udf: do I only include the condition to switch from vaporization law to my user-law, or do I also need to include the condition to switch between the built-in inert-heating and vaporization laws? In latter case, the controling parameter is DPM_VAPOR_TEMP(p,m), then how can I get the pointer m?

Any help or suggestions would be much appreciated. Thank you in advance!

ljp

[ljp]

I tried several ways but none of them can give me correct field:

1. putting the inert-heating, vaporization law as the 1st and 2nd law, and my user-law as 3rd law, default dpm-switch ------ wrong results;
2. putting my user-law as 1st law, and make other laws inactive, using my own dpm-switch ------- wrong results;
3. putting my user-law as 1st law, inert-heating as 2nd law, vaporization as 3rd law, using my own dpm-switch ------- wrong results;

I think something is wrong with my dpm-switch udf, especially the part for switching between the built-in laws, I list the relavant part below. Has anyone used the custom laws before? could you help me here?

DEFINE_DPM_SWITCH(dpmlaw_switch, p, ci)
{
Material *m;

if(P_T(p) < DPM_VAPOR_TEMP(p,m))
P_CURRENT_LAW(p) = DPM_LAW_INITIAL_INERT_HEATING;
else if(specific condition)
{
if(P_T(p) < DPM_BOILING_TEMPERATURE(p,m))
P_CURRENT_LAW(p) = DPM_LAW_VAPORIZATION;
}
else
P_CURRENT_LAW(p) = DPM_LAW_USER_1;
}

Thanks a lot!

ljp

[sreerao]

Hi IJP,

I am facing similar probelm with DPM_SWITCH. Did you find any solution for your probelm. Would you like to share it with me please?

Sreerao

[ljp]

Hi Sreerao,

finally on the custom-law panel, I set the inert-heating law as 1st law, vaporization law as 2nd law and user-law as 3rd law. and included the switch between these laws. Then when I included the gravity effect and the breakup model, the results looks what I'd expect. But honestly I'm still not sure whether this is correct until I can have some experimental measurements done.

regards,
ljp

[Sowmi]

hi Ijp
what was your 3rd user law other than heating law and vapourization law. Can you guide me to write the udf for custom law or any sample code. I studied the udf law example in udf user guide but it is very confusing.

Thank you in advance.