apply different flow rate in two inlet in Fluent with varying time

[dgp234]

Hi all.

Currently, I am doing micro valve analysis which contains two inlets. the conditions I have to apply in those inlet are different flow rate with varying time.

For example,

Inlet-1 = 8 ul/min mass flow rate from 0-3 seconds.

inlet-2 = 4 ul/min mass flow rate from 3-6 seconds.

My question is whether I have to create UDF to solve this or any default option is available in Fluent.

thanks in advance

Kind regards
dgp

 

[hendersdc]

Fluent allows you to define time varying properties around inlets in transient analyses. I can't remember off the top of my head if volume flow rate is something you can set or if you will need to convert it to a velocity though. This shouldn't be hard if you know the cross sectional area of your opening. You can then enter the variable flow rate as a sets in a text editor separated by spaces where the first number is time and the second number is flow rate like this:

Inlet 1
0 8
3 8
3.1 0

Inlet 2
0 0
2.9 0
3 4
6 4
6.1 0

You can check the values in a graph to see if everything looks right but I find inputting them to be easier in the text editor. You will need to be sure you specify the units correctly. You will also need to include ramping up and down of the flow rate as I have shown in the example since Fluent won't accept two flow rates at the same point in time. I used a 0.1 second ramp but you can make it much smaller.