### 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 - william

Pages: 1 [2] 3 4 ... 11
16
##### Fluent / Re: How can I calculate time-average velocity in transient simulation?
« on: November 21, 2012, 10:05:10 AM »
The UDF needs to be compiled. You can not interpret it.

17
##### Fluent / Re: gas escape from stirred tank
« on: October 11, 2012, 09:33:47 AM »

18
##### Fluent / Re: gas escape from stirred tank
« on: October 10, 2012, 07:35:53 PM »
What is your inlet boundary condition?
Make sure that the pressure at the outlet face is smaller than upstream pressure.

You can set mass outflow as the outlet boundary condition if you don't have backflow at the outlet.

19
##### Fluent / Re: Solver for vortex tube simulation
« on: September 24, 2012, 11:58:04 AM »
The selection of the solver is based on whether the fluid is compressible or incompressible. Even the gases can be considered incompressible if the pressure gradient in the flow is not large enough to change the density significantly. But if you have a large pressure gradient or if the fluid has mach number greater than 0.3 then density based solver is preferred.

20
##### Fluent / Re: DPM and granular Eulerian-Eulerian: particel size verses computational cell size
« on: September 12, 2012, 06:25:12 PM »
You can do three test cases, one in which cell size is smaller than particle size. Second one in which both are comparable. Third one in which cell size is greater than particle size.

Before doing these cases, make sure that the single phase result is independent of these mesh sizes.
Because if the results of single-phase-only-flow is also changing with these three grid sizes then you can not reach a conclusion whether it is because of the grid size/discrete phase size ratio or because of the continuous phase flow dependent on the mesh size.

21
##### Fluent / Re: How can I get particles mean diameters at each cell?
« on: August 29, 2012, 11:21:03 AM »
You can get an estimated solid volume fraction in a cell by diving discrete phase concentration with particle density (assuming that all particles have the same density).

This will be:

C_DPMS_CONCENTRATION(c,t)/P_RHO(p)

You may get a value greater than 1 in certain regions if your case involves dense discrete phase flow.

22
##### Fluent / Re: How can I get particles mean diameters at each cell?
« on: August 29, 2012, 09:00:03 AM »
You will have to compile the UDF you can not run it as interpreted because it uses variables.
You will need to sort out the issues with compiling.

23
##### Fluent / Re: How can I get particles mean diameters at each cell?
« on: August 28, 2012, 06:23:17 PM »
You will need to define additional UDMs for this purpose.

The particle velocities at cells can be stored using:

P_VEL(p)[0] ---> x component of particle velocity
P_VEL(p)[1] ---> y component of particle velocity
P_VEL(p)[2] ---> z component of particle velocity

24
##### Fluent / Re: UDF for population balance method
« on: August 25, 2012, 11:05:17 AM »

25
##### Fluent / Re: How can I get information about aerodynamic forces and moments (lift, drag)?
« on: August 24, 2012, 09:33:07 AM »
Use the forcepanel, which is a free add-on to Fluent 12. After reading the scheme you will get an entry in Reports/Resultant Force. You can write out lift, drag, coordinates of CG, force, moment vs iteration or vs flow-time in a separate file. Enable "moving body coordinate system" and the "print to file". Now open the dynamic mesh panel, and confirm the moving zone with "create". This ensures that the force panel recognices the zone motion. In the force panel click on "update" and "print". If you start the simulation now, an external file will track the quantities.

26
##### Fluent / Re: moving wall problem
« on: August 24, 2012, 09:12:13 AM »
See the tutorial in the PDF attached. You will need to make a UDF for this purpose as well.

27
##### Fluent / Re: DPM: How to attach deistinctive property for a particle
« on: August 19, 2012, 08:25:23 AM »
This looks fine but you should use user defined scalar as defined above to store the particle property instead of using UDM, because UDM will store it in the cell not in the particle tracks.

28
##### Fluent / Re: DPM: How to attach deistinctive property for a particle
« on: August 18, 2012, 01:36:35 PM »
You can define that inside the equation using "if and else" statements, like,

if (P_DIAM(p)<=XX.X){
P_magnetic_sat(p)=XXXXXX;
}else if(P_DIAM(p)>=XX.x){
P_magnetic_sat(p)=XXXXX;
}

and so on..

29
##### Fluent / Re: DPM: How to attach deistinctive property for a particle
« on: August 17, 2012, 09:52:46 AM »
Inside the DPM_SCALAR_UPDATE macro you can use user defined scalar to store the property of material at each time step. You can even plot the trajectory of that property in the particle tracks option.
You will need to enable user define scalar in fluent.

#define P_magnetic_sat(p) P_USER_REAL((p),0)
for second user defined scalar, add
#define P_magnetic_sat1(p) P_USER_REAL((p),1)

and so on.

Then in the DPM_SCALAR_UPDATE macro add the equations that define P_magnetic_sat(p) and P_magnetic_sat1(p)

In this case you will need to enable 2 user defined scalars.

30
##### Fluent / Re: DPM: How to attach deistinctive property for a particle
« on: August 16, 2012, 11:29:20 AM »
Use DEFINE_DPM_SCALAR_UPDATE macro to change the property of the particle.
See Fluent UDF manual for examples of DEFINE_DPM_SCALAR_UPDATE.

Pages: 1 [2] 3 4 ... 11