Time-averaged velocity plot for a transient simulation
 

Hi,

I want to plot a time-averaged cross-sectional velocity profile plot.

I can plot the velocity profile for a specific time, but how do can I plot time-averaged velocity profile for a specific range of time interval.

Can any one help me?

Thank you.

Hi,
I've done it but it's not very easy at least in ver. 6.3.
you can export your data and find the average flow in another software like MATLAB and then prepare it for fluent interpolation or showing in Tecplot.

Bests,

I have version 12.1
So, I have to export the data for each time step and get an average value in other software like excel? That will be an extremely painstaking when the averaging interval is very large and time step size is very small as in my case.

:eek:

There must be some easy way of doing it in Fluent 12.1

:confused:

It is available in fluent

How can I do it? I could not find this feature in ver. 12 :confused:

I've done it by automation in both FLUENT and post processor. so it's not very complicated or time consuming.

Bests,

I want to add another way if you haven't run your case yet.
you can also store your desired variables in temporary memory e.g. UDM and then find your average flow without using extra softwares (but I didn't use this procedure before). My previous suggestion is more proper for the cases with saved data in previous simulations.

Bests,

Average velocity at all point along the pipe/ Calculate mass flow rate along pipe
 

Hi,

Is it possible in fluent 14.0 to calculate average velocity after certain time step ( say after every 50 time step) at all point along the pipe, so that I can calculate mass flow rate along the pipe after certain time ?

If anyone has done this type of work or has any idea, please let me know. That will be great help.

Thanks in advance.

Tanjina

First of all, I would like to mention that there is a "data sampling for time statistics" in fluent.
Find the checkbox in the "run calculation" tab.

I actually dont know if the start of the sampling process can be delayed automatically. But what you can do is run your simulation to the point where you want to start the data sampling and activate the data sampling manually at this point.

Thank you Flotus. I am sorry, I couldn't get your message. By data sampling, is it possible to calculate average velocity at every node along the 2D pipe? I need it badly. :( Would you please explain a bit more ?

When data sampling is enabled, you get the time-averaged variables for the whole flow field (and some more quantities, refer to the manual for details) as a result of the simulation.

Thank you Flotus. I have read the article on user manual. I have one question. How can I custom field function ?

And another question is, in fact I need area averaged velocity after certain time step.( i.e. every 50 step). Is it possible by Data sampling for time statistics option ? Sorry, I tried to understand from manual, but I couldn't. And it is not possible by Data sampling for time statistics , have you any idea how can I do that ?

Thanks in advance.

Regards,
Tanjina.

The area-averaged velocity (and much more, the GUI is quite self-explanatory here) can be created in the "monitors" tab in fluent.

I bet that you can also access custom field functions here.

Hello Flotus,

Thank you very much for your reply.

I tried to plot velocity in every iteration from "Monitors", but is it the area averaged velocity ? It's only showing that "velocity magnitude", that's why I got confused.

I have pipe with 0.2 width and 6 m long. I want to calculate average velocity along 6 m at every node point. Is it possible by "monitors" tab? if not, then is there any other way ? By using that average value I will calculate the mass flow rate along the pipe.

I am sorry, may be it's a silly question..... but I couldn't find out it by myself. Hope you can help.

Thanks in advance.


Regards,

Tanjina

The monitor shows whatever you insert.
Please have a close look at the GUI and the possible settings when adding a new surface monitor. It really is self-explanatory.
There is even a "Mass Flow Rate" report type among the surface monitors...

Thank you Flotus for your suggestion. :) Finally I found my way. Thanks a lot.

Find area averaged velocity along 3D pipe
 

Dear Flotus and All,

Right now I am modelling a 3D pipe surrounded by aggregate. I need to find area averaged velocity along pipe length ( X-axis). According to my understanding I have to find out the area averaged velocity of y axis at every x point.

Is there anyone who can kindly suggest me any idea? I would be really grateful. Thanks in advance.

Regards,
Tanjina

hi FAR,please explain about it?
thanks

Hi

I run a large eddy simulation in fluent 14. I saved my case and data files at different time steps every 50 time steps and I run the simulation for 1000 time steps. Can anyone tell me how I can find an average value of a variable lets say velocity from all of the files that I saved?

I do not want to open them one by one and put into excel or any other place to take the average of a variable. Is there any way that fluent can read those by itself and calculated the average?

Thank you,

Hello maphd,

I don't know any way to do this on Fluent, but using Matlab, you can do that easily. Matlab will read your saved file first and then will calculate the average velocity over time.

Regards,
Tanjina

how have it done?
steps, please

Hello Mali28.


I've been working on the same problem for the past couple days. Here's what I have so far.


I am using ANSYS FLUENT 19.2. I am doing a 2D transient simulation of two mixing flows: gas and water. Water boundary conditions are steady, gas boundary conditions (pressure and velocity) are transient.
First of all, it turns out that FLUENT does not do 2D simulations exactly. I.e. when I did meshing and solved the problem, I saw that FLUENT automatically converted my 2D schematic to a 3D one with a width equal to a mesh cell width. That's what helped me to do area averaging.
Overall:

1) I opened workbench.
2) I did geometry --> then I did mesh --> then I did setup --> then I did solution
3) Then I exited solution and returned back to the workbench
4) Then I opened results

5) In results: Location --> Plane
6) It will offer you several options to create a plane
7) There will be an option to define a plane perpendicular to z axis and parallel to xy plane (it is for my case - you can choose other options), also it will allowg you to define the sizes of your plane

8) I did 2D. Therefore, the length of my plane was equal to the width of my geometrical 2D form - it is easy to guess
9) But what about the width of my plane? The width is equal to the mesh cell size which I specified in the setup for my solution
10) That's how I created a cross sectional plane in which I wanted to find cross sectional averaged pressure
11) Go to "function calculator". It's icon looks like an "f" in front of a calculator. It's at the end of the same row in which "locations" are placed.
12) There, under the section "Function Calculator" you will see different options: "Function", "Location", "Case" and so on. You need "Function".
13) In "Function" choose "areaAve".
14) Then hit "calculate"
15) You will see your area averaged pressure (In my case I needed pressure - you can do whatever you want).


So, the overall idea is very simple and simultaneously hard to guess. Whenever you need to do area averaging AFTER your calculations have been done, first create a plane in which you will be doing your averaging, second, use "Function Calculator".