Turbulent intensity field function: Floating point exception [divide by zero]

Bin · April 16, 2015, 01:37

Hello to all CFD mates,

I wish to define a Turbulent Intensity (TI) scalar in Star-CCM+ so that I can study the turbulence better. However, I receive a floating point exception [divide by zero] error when I created a TI field function. The function's definition is: sqrt((2/3)*$TurbulentKineticEnergy)/(mag($$Velocity))

From the definition, it is clear that the zero velocity at the wall is the main issue that need to be considered when defining the function. I was thinking to redefine the function where it returns zero value to system when it is divided by any zero value, or maybe return zero value when TI equals to infinity. But I have no idea whether this can be done or not.

I am still seeking for a solution to modify the solution. At the same time, I hope anyone that has experiences in this type of issue can provide some advises that help me to solve the problem.

Many thanks in advance.

ab.glb.cfd · December 27, 2015, 21:57

Hello STAR-CCM+ user,

In the properties window you have to tick mark the "ignore boundary values" option to avoid Divide by zero error message.

Hope this helps and answers your question.

April 16, 2015, 01:37	Turbulent intensity field function: Floating point exception [divide by zero]	#1
Bin Member Chan Hiang Bin Join Date: Apr 2013 Posts: 44 Rep Power: 13	Hello to all CFD mates, I wish to define a Turbulent Intensity (TI) scalar in Star-CCM+ so that I can study the turbulence better. However, I receive a floating point exception [divide by zero] error when I created a TI field function. The function's definition is: sqrt((2/3)*$TurbulentKineticEnergy)/(mag($$Velocity)) From the definition, it is clear that the zero velocity at the wall is the main issue that need to be considered when defining the function. I was thinking to redefine the function where it returns zero value to system when it is divided by any zero value, or maybe return zero value when TI equals to infinity. But I have no idea whether this can be done or not. I am still seeking for a solution to modify the solution. At the same time, I hope anyone that has experiences in this type of issue can provide some advises that help me to solve the problem. Many thanks in advance.

December 27, 2015, 21:57	TI field function in STAR-CCM+	#2
ab.glb.cfd New Member Abhijit Deshpande Join Date: Jan 2014 Location: Bangalore Posts: 7 Rep Power: 12	Hello STAR-CCM+ user, In the properties window you have to tick mark the "ignore boundary values" option to avoid Divide by zero error message. Hope this helps and answers your question. sathishkrazy and PulpC like this.

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