Discussion Forum

(all are illustrated in the .doc file)

Hi, everyone,

I add an extrusion coupling operator to extract the dependent variable at a specified boundary with the name of “genext1”. According to the guidance of the document (user’s guidance), I build the extrusion operator in the model and defined a global variable with the name of “TD1” to check whether there is wrong with the operator. All the details are shown in Fig.1, including Fig. (a) and Fig.(b).

(all the figures are shown in the attachment, thanks.)



After solving the model, I try to visualize the global variable “TD1”, while there are some problems.
Fig. 2 shows the resultant temperature distribution. Because there is heat flux (BC) on the upper boundary, hence the maximum temperature should locate on this boundary.
However, I try to plot “TD1” using line plot and surface plot, only to fail. Fig. 3 shows the results and errors when plot the “TD1” using line and surface plot. In Both situations, the
“Unknown function or operator
-Name: genext1
-Plot: surf1 (Surface)”
error occurs. I am quite puzzle with it. I have defined the global variable “TD1” using the genext1 (general extrusion) operator, and plot the global variable, but fails. The extrusion operator can create a global quantity which can be used in other model. Can it be used in the global definition? This is my first question, thanks for your help.

Afterward, I try to use the “genext1(T)” in the expression instead of T (which is defaulted), and both plots using line and surface plot are ok, just shown in Fig. 4. But after a careful look, the so called boundary temperature (upper surface temperature) is different from the one shown in Fig. 2. The maximum temperature at the upper temperature is 1.0451 X 10e4, while the one obtained through the extrusion operator is 1.0557 X 10e4. The gap (105K) is a little big. I haven’t understood the underlying reason and mistake. Could you give me some guidance?

Question one:
Can the extrusion operator be used in the global definitions?
If can, why I can’t plot after solving?

Question two:
Why there is a big difference between the actual/theoretical temperature and the one obtained through the extrusion operator?

Thanks sincerely in advance.
Best wishes to you and your family.

Yours
FM Huang
Dec.19th, 2011