Learning Forum

[Kasambila]

Hi friends,
so I have a fairly simple setup: I have 3 bottom inlets that let hot water (370 Kelvin) flow into colder water (280 Kelvin).

Currently I have the velocity magnitude set to 0.3 m/s but now I would like to make it time dependent.  
As a first step I simply want to set the velocity magnitude of the inlets to equal the time in s.  
How would I go on about doing that. I already looked in the users guide but honestly couldn't really find anything and google was of no help either.  
How do I reference t (in seconds) in the simulation?  
The expression should basically look like this:  "t [m s^-1]" but that results in an error.  
Can anyone help me out?

 

Edit. So in the end I would like to make a velocity magnitude that appears somewhat random. So that the inlet always keeps changing its velocity every time step; maybe between 0 - 1 m/s

[Karthik Remella]

Hello,

The final units of velocity have to be [m s^-1]. Therefore, the units of your input value must be adjusted appropriately.

t * 1 [m s^-2] = t [m s^-1]

Could you please try the following?

Thanks.

Best,

Karthik

[Karthik Remella]

Could you share a screenshot of your formula?

Thank you.

[Kasambila]

Thank you very much, it seems to work.  
after 67 time steps of 0.1 seconds I get a "floating point exception" and the calculation stops.  
I think this maybe has to do with the high values of the velocity magnitude?  
Now I would like to introduce a modulo in my calculation, is this possible?  

The basic idea being that I simply can us velocity magnitude = t(in s)%10.
I've seen that the expression editor offers a "mod(," but I dont get it to work.  
I've tried the following: "mod(1[m s^-2], 10)" but it once again says "Syntax Error: Incomplete expression term"