| Author | Message | ||
     Robert Duckworth (rdt) New member Username: rdt Post Number: 1 Registered: 05-2004 |
I am looking at setting an upper limit on a temperature in a transient heat transfer problem since my properties are limited to a given temperature range. Is there a way to put a limit, say in the constraint section, or am I stuck with letting the time interval to continue? | ||
| Robert G. Nelson (rgnelson) Moderator Username: rgnelson Post Number: 149 Registered: 06-2003 |
It's not clear to me whether you want to force temperature values to remain less than a limit, or to stop the computation when the temperature exceeds a limit. 1) you can keep values within a prescribed range simply by programming sources or sinks that are zero until the range is exceeded, and then come into play to drive the value in the desired direction. Use a RAMP or SWAGE or other smooth transition, so that jumping across the switch point does not drive the timestep down. Bear in mind that any such modification adds or subtracts energy from the system by non-physical processes. 2) you can merely limit the arguments to parameter computations, so that the parameter value remains constant at the limiting value for all arguments outside the prescribed range, e.g. PARAM = PARAMFUNC(MIN(MAX(U,Umin),Umax)) 3) you can halt the computation when a value exceeds a limit: HALT (GLOBALMAX(U) > Umax) | ||
| Robert Duckworth (rdt) New member Username: rdt Post Number: 2 Registered: 05-2004 |
You are right on the first count. Stop computation when a temperature exceeds a limit. Tried no. 3, but an illegal symbol error comes up. the actual line is "halt(globalmax(temp)>100)" or halt(globalmax(temp)>tmax). We are using version 2.22a if this makes any difference in syntax. |