Show Posts

This section allows you to view all posts made by this member. Note that you can only see posts made in areas you currently have access to.

Messages - lakhi

Pages: [1]
Meshing / Re: structured vs unstructured
« on: August 11, 2012, 05:22:03 AM »
Help please!

Fluent / Re: UDF for discrete phase model
« on: August 11, 2012, 05:21:21 AM »
Anybody! Some idea how to sort out the problem?????

Meshing / structured vs unstructured
« on: August 07, 2012, 08:20:04 AM »
Hi. I'm using ICEM CFD for mesh generation. After meshing, i save it as unstructured mesh. There is one more option called blocking mesh. Is this format for creating structured mesh? Does Fluent run structured meshes (so far as i know, fluent is an unstructured mesh solver)? If yes, how. Which one is best for yielding better results, structured or unstructured. I'm using ANSYS v14 at present.Thanx in advance.

Fluent / Re: UDF for discrete phase model
« on: August 07, 2012, 08:03:58 AM »
Thanx mali28, I got it. As in your last line"The number of tracked particles should not decrease at the end of simulation if your injection is continuous.", you are right ! That is what is making me to think about my approach. If I set mass flow rate and velocity in the dpm with normal to face injection and if I set start (as 0) and stop time (as 0.5 sec) my solution does not converge and number of particles tracked is very high. Moreover DPM iteration takes toooo long and fluctuations takes place in residuals. That is the reason why I asked that Is it possible to inject a certain number of particles and then keep the track? I'm really upset with my problem and I'm unable to figure it out. Any suggestions regarding DPM injection please !  Efforts will be praised.

Fluent / Re: UDF for discrete phase model
« on: August 06, 2012, 03:18:05 PM »
Thanx mali28 4 reply. The thing is that I set mass flow rate and velocity in the dpm with normal to face injection and I didn't set start and stop time (both by default 0). At the end of simulation it says like "particles tracked = 760" and "particles trapped = 0" and "particles escaped = 0". In the mid of the problem I have something like "particles tracked = 86907" and "particles trapped = 208" and "particles escaped = 4" and so on. This means my particles tracked value goes on decreasing at some interval till the end. Am I doing something wrong? Is it possible to inject a certain number of particles and then keep the track? Plz. help !

Fluent / UDF for discrete phase model
« on: August 06, 2012, 02:45:51 PM »
Hi. I'm working with air dust mixture. Does anybody have udf (or tell me some other way) to find the number of dust particles trapped in and number of dust particles escaped from a cyclone from the start till the convergence of the problem? The particles have a range of diameter. I'm not a programmer, so I need help. Efforts will be highly appreciated.

Thanx infocfd, I finally got it.

Fluent / Re: DPM Injections
« on: July 14, 2012, 05:28:13 AM »
Hi william

Thanks for your effort too !

Fluent / How to get time average tangential velocity in swirl flow.
« on: July 14, 2012, 05:23:10 AM »
I'm working on the swirl flow and I'm not able to get desired time average tangential velocity. It is said that in swirl flow, where tangential component is not independent and is coupled to pressure, simply time averaging the tangential velocity (as is represented in FLUENT) is not the actual procedure. All I need to have is the x-velocity "vx" , the y-velocity "vy" and the z-velocity "vz" . The mean z-velocity "vz" is same as the mean axial velocity "vaxial" . The mean tangential velocity "vθ" is to be obtained using Fluent custom field function:

vθ = vx cos θ + vy sin θ

where "vx" is the time averaged x-velocity, "vy" is the time averaged y-velocity and "θ" is the angular coordinate.

Now when I open Fluent custom field function, nowhere i can find "θ". The above expression tells that the coordinate system used is the Cartesian coordinate system because tangential velocity vθ is expressed in terms of vx and vy. But how to express this "θ". Do I have to write a UDF for this? If yes, how  :-[ . Suggestions will be appreciated.

Fluent / Re: DPM Injections
« on: July 14, 2012, 04:55:35 AM »
Thanks RodriguezFatz.

I'll try the same. Hope now I'll get some results.

Fluent / DPM Injections
« on: July 11, 2012, 05:38:19 PM »
Using DPM, if I want to inject, say, 2000 particles from inlet and simulate to get the results, what I have to do in FLUENT 14?
How to keep track of the particle positions?
There is an option in FLUENT "Injection-Type: group", where the variables, namely: x-,y-, and z-positions are required for first point and last point. What are these first point and last points.
For surface type injection, we have, start time and stop time. I guess there are injection time (discrete phase injected for 5 sec) in the continuum phase. If this is true, how does FLUENT inject discrete phase? I mean if I choose "start time = 0" and "stop time = 5 sec", how will FLUENT react to these time variables. I think it won't inject desirable number of particles.
I'm not very familiar with DPM, so please explain me in details.

I think the built-in option in Fluent  "Custom Field Function" can solve the problem. After defining the desired parameters, use "data sampling" to average-out those parameters.

Pages: [1]