Learning Forum

[ananyas]

Hello,

 

I use Ansys 2019R1 w/ academic license. I am relatively new to Fluent. I wanted to generate sinusoidal pressure pulse as the input. I understand that there are three ways to implement this:

1. plotting the function w.r.t. time, tabulating it and using the result table directly.

2. User defined functions

3. Expressions

My queries are:

1. For convenience to my purpose, I am using expressions. I referred https://www.ansys.com/blog/tips-and-tricks-enter-expressions-into-ansys-fluent-ui. I don't understand the syntax of the expression. Why is it written as sin(Time/)? As in why the seconds as inverse? Please explain the syntax briefly. How can I provide a pressure pulse of the form Asint(wt + x) [Pa]?

2. Please link a document/research paper giving the details of expression synatx.

3. I have to use a square wave pulse later. I see that it's not possible to use sgm function in the expressions. How can this be achieved?

 

 

[Karthik Remella]

Hello The idea behind using expressions is to make sure your final units are consistent with the physical quantity you are trying to write an expression for. In fact, expressions are validated to ensure they have consistent unit types
Here is the link to the Fluent User Guide, where you should find all the necessary information.
https://ansyshelp.ansys.com/?ReturnUrl=%2FViews%2FSecured%2Fcorp%2Fv202%2Fen%2Fflu_ug%2Fflu_ug_expression_syntax.html
Regarding your question related to a square pulse, perhaps, you can use IF conditions for the pulse. Please let us know if this works.
Thanks.
Karthik

[DrAmine]

1/To get ride of the time dimension

2/Fluent User's Guide is good ressource. I will recommend to update to 2020R2 if possible as many new things regarding Expression were made possible

3/Signum not there but you might use boolean like IF to do similar.