Note: This discussion is about an older version of the COMSOL Multiphysics® software. The information provided may be out of date.
Discussion Closed This discussion was created more than 6 months ago and has been closed. To start a new discussion with a link back to this one, click here.
CFD -turbulent flow
Posted Nov 2, 2014, 5:45 p.m. EST Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.3b 1 Reply
Please login with a confirmed email address before reporting spam
Hi
I would like to insret in a tank-pipe model a velocity function that starts from 30m/s goes to 60m/s 90m/s and so on until 300 m/s. I was trying with step fnction but I didnt manage it. I am new at comsol so any help is very welcome.
Thank you in advance.
with regards
Dionisios
I would like to insret in a tank-pipe model a velocity function that starts from 30m/s goes to 60m/s 90m/s and so on until 300 m/s. I was trying with step fnction but I didnt manage it. I am new at comsol so any help is very welcome.
Thank you in advance.
with regards
Dionisios
1 Reply Last Post Nov 4, 2014, 8:44 p.m. EST
Please login with a confirmed email address before reporting spam
Posted:
10 years ago
There are two approaches depending on your needs and the stability of your model.
If you need only stationary results at each of these values and your model is well-behaved, then set up a Parametric Sweep. This will allow you to define your set of values (e.g. 30, 60, ...). The model will be solved at each value.
If you need the time-dependent solver, for example if you need to change your boundary condition slowly if convergence is difficult, then you can set up an Analytical function consisting of the sum of smoothed step or Heaviside functions (e.g. flc2hs), each with an offset and rise interval that will allow you to create a series of plateau values connected by smooth transitions, corresponding to your values of 30, 60, etc.
I have used such a function before in one of my models. If you need, I can share it with you.
--
Steven Conrad, MD PhD
LSU Health
If you need only stationary results at each of these values and your model is well-behaved, then set up a Parametric Sweep. This will allow you to define your set of values (e.g. 30, 60, ...). The model will be solved at each value.
If you need the time-dependent solver, for example if you need to change your boundary condition slowly if convergence is difficult, then you can set up an Analytical function consisting of the sum of smoothed step or Heaviside functions (e.g. flc2hs), each with an offset and rise interval that will allow you to create a series of plateau values connected by smooth transitions, corresponding to your values of 30, 60, etc.
I have used such a function before in one of my models. If you need, I can share it with you.
--
Steven Conrad, MD PhD
LSU Health