[Dyls]

Hi

I have created a user defined function and am unable to figure why it will not compile.

What is wrong with my syntax?

(($time > 16560) && ($time < 79200)) ? 0.00003*($time/3600)^5 - 0.0018*($time/3600)^4 + 0.044*($time/3600)^3 - 0.4912*($time/3600)^2 + 2.727*($time/3600) - 4.9577 : 0

Also, what is a good resource on learning the syntax for these functions? I checked the star-ccm+ documentation but it looks like only a few examples are given. I couldn't find anything else.

Thanks

Dylan

[kguntur]

starccm+ does not recognise "^". use pow(x,y) to represent x^y. that should work.

[olesen]

Originally Posted by Dyls

Hi

I have created a user defined function and am unable to figure why it will not compile.

What is wrong with my syntax?

(($time > 16560) && ($time < 79200)) ? 0.00003*($time/3600)^5 - 0.0018*($time/3600)^4 + 0.044*($time/3600)^3 - 0.4912*($time/3600)^2 + 2.727*($time/3600) - 4.9577 : 0

Also, what is a good resource on learning the syntax for these functions? I checked the star-ccm+ documentation but it looks like only a few examples are given. I couldn't find anything else.

Thanks

Dylan

As was mentioned, use pow() for these functions - this is consistent with standard C/Java syntax. For polynomials, however, you can avoid pow() and just do it directly. This should be slightly more efficient.

Eg,

c0 + x*(c1 + x*(c2 + x*(c3 + x*(c4 + x*(c5)))))

Also note that the ternary operator is not extremely robust. You might consider placing things within brackets or splitting it into a separate functions.

[sabrina]

Originally Posted by olesen

As was mentioned, use pow() for these functions - this is consistent with standard C/Java syntax. For polynomials, however, you can avoid pow() and just do it directly. This should be slightly more efficient.

Eg,

c0 + x*(c1 + x*(c2 + x*(c3 + x*(c4 + x*(c5)))))

Also note that the ternary operator is not extremely robust. You might consider placing things within brackets or splitting it into a separate functions.

thanks for these informations, I have a problem if you have any idea, in star CCM+ we can calculate or define the derivative of function ?, like the derivative of the temperature or of the velocity (du/dy) or (dt/dy), I want calculate temperature jump and slip velocity

[Pkanugov]

Hello everyone,

I am trying to create a variable density ( varying with height ) profile in a rectangular domain and the equation I'm using is:

0.2257*(pow($$Centroid[1],3))-0.4868*(pow($$Centroid[1],2))+0.06016*(pow($$Centroid[1],1))+1.301

I'm first generating a report using the expression and when I try to run the report ( after initialization ) I get an error saying:

Cannot evaluate field function Centroid.

Can someone please help me with this.

Thank you in advance.

[278780870]

Does anyone know how to change the pressure field to field function definition in starccm +? I define a static pressure, but I find that the system always reports an error: "unable to compute field function 'name' on 'region'. Please check that the function is defined here"It seems that the pressure field cannot be changed and can only be set as a function

[mCiFlDk]

Originally Posted by Pkanugov

Hello everyone,

I am trying to create a variable density ( varying with height ) profile in a rectangular domain and the equation I'm using is:

0.2257*(pow($$Centroid[1],3))-0.4868*(pow($$Centroid[1],2))+0.06016*(pow($$Centroid[1],1))+1.301

I'm first generating a report using the expression and when I try to run the report ( after initialization ) I get an error saying:

Cannot evaluate field function Centroid.

Can someone please help me with this.

Thank you in advance.

Dear Pkanugov,


Have you found the solution to your problem?


Thank you!