Choosing the right monitor points
 

Being a newbie to CFD, I lack the proper understanding in identifying the quantities of interest to be monitored while a run is in progress. I mean I’m not clear with identifying the right quantities in a CFD analysis which tend to be really crucial that their variation needs to be monitored while the run is in progress to judge the reliability of the convergence obtained.

Can some one please suggest me upon this by quoting the instances of some typical CFD problems. As of now I’m working upon the cfd analysis of hot air flow in a cooking oven. For this problem i'm considering quantities like volumeAve(Temperature)@FLUID , massFlowAve(Temperature)@Trays to monitor.

The purpose of CFD is to conduct a numerical experiment. So in your experimental model what parameters are of interest that you would like to measure? This is why you need to define WHY you are doing the model before you start anything. After you know why you are doing a model the important parameters should be apparent.

So WHY are you modelling the oven? Are you checking for temperature unevenness? Or finding out how hot the outer surface gets? Or seeing how fast a roast turkey cooks inside? Each of these purposes would demand different outputs.

Ok, if the case is like I'm interested in knowing how fast the oven cooks the chicken grill and considering some other case of an electronics cooling problem where in I'm interested to know the rate of heat dissipation from a IC chip into it's surroundings.

So for these cases can you please suggest me upon the monitor points to choose.

Then put a temperature monitor point in your chook and a temperature monitor point on your IC.

Can you please tell me when to use a point and when to use an expression to monitor the quantities of interest in the simulation. I mean if i'm interested in knowing the rate of heat dissipation from the IC chip. Then should I use a point on the IC chip surface to monitor the temperature (or) do I need to go with something like: areaAve(Temperature)@ICchip.

Really the issue is about engineering judgement. You need to decide what is the best way to report the result.

Glenn, in the electronics cooling problem I was referring to, some surfaces of the ICchip are Fluid solid interfaces and the others form Solid Solid interfaces sol if i'm interested in monitoring the area averaged Temperature for the whole ICchip , then how do you suggest me to proceed ?

Then calculate the areaAve(T)@surface - isn't that obvious?

ok ill try it that way

Can I use the expression areaAve(Wall Heat Flux), to monitor the area averaged heat flux at an interface( fluid-solid (or) solid-solid) (or) is it confined to monitor heat flux on a wall.

Well, I checked it out and I found that areaAve(Wall Heat Flux) can be applied to sides of the interfaces also rather than to wall boundary type alone.