Hello all

I am working on CFD simulation of syngas deposition on a high pressure turbine vane. While going through literature on this topic, I found that FLUENT 4.4.7 is the best version for this study as the particle-wall interaction is more realistically modeled in this version than in FLUENT 5. FLUENT 5 uses rebounding/sticking for all particles while 4.4.7 allows the condition of the particle at the surface to be determined by user defined subroutines. I want to know if FLUENT 6.3 has the capability of 4.4.7 in this area. If not, what are my options?

Thanks,

Prashanth

Yes, you can use a user defined function to specify the fate of a particle when contacting a wall in Fluent 6.3.

We had several subroutines for this purpose which we ported directly from Fluent 4 to Fluent 6, bypassing version 5.

By the way, hopefully Fluent 12 will released in the first part of this year, which does provide some additional features.

[eloy785]

hi

I'm working with fluent 6.3.26 and i want to know if i can put an specific quantity (KG) in a specific wall and then set a velocity inlet in order to carry out the particles in the wall.

regards

[Jovana]

Originally Posted by Allan Walsh
;156106

Yes, you can use a user defined function to specify the fate of a particle when contacting a wall in Fluent 6.3.

We had several subroutines for this purpose which we ported directly from Fluent 4 to Fluent 6, bypassing version 5.

By the way, hopefully Fluent 12 will released in the first part of this year, which does provide some additional features.

Hello, I need some info. I am new in this UDF codes, without knowledge in FORTRAN or C language. Any way, I have found a code that I can use for particle - wall Interaction USREFL.F that is used in Fluent 4. I am working in Fluent 6. How can I use this code?

Regards!

[fariba.j]

hi,
I want to model deposition of particles by thermophoretic force and brownian diffusion in laminar flow. i want to use euler-euler approach,but i dont know which of these models i must use,species model or multiphase model.also i work with fluent 6.3.26
thanks a lot

[Amir]

Originally Posted by fariba.j

hi,
I want to model deposition of particles by thermophoretic force and brownian diffusion in laminar flow. i want to use euler-euler approach,but i dont know which of these models i must use,species model or multiphase model.also i work with fluent 6.3.26
thanks a lot

Dear Fariba,

If you want to use Eulerian approach; you can perform UDS equation as a simplified form of species transport; here, the diffusion term plays the brownian role.

Bests,

[fariba.j]

Originally Posted by Amir

Dear Fariba,

If you want to use Eulerian approach; you can perform UDS equation as a simplified form of species transport; here, the diffusion term plays the brownian role.

Bests,

hi
thanks for your answer,i think i need udf to add thermophoresis term to uds,also uds is for single-phase
if I want to model coagulation of particles with their thermophoresis deposition,i have to use population balance,for this case,i have to add themophoresis & brownian diffusion terms to this equation with a udf,is that true??? pleas help me
thanks

[Amir]

Originally Posted by fariba.j

hi
thanks for your answer,i think i need udf to add thermophoresis term to uds,also uds is for single-phase
if I want to model coagulation of particles with their thermophoresis deposition,i have to use population balance,for this case,i have to add themophoresis & brownian diffusion terms to this equation with a udf,is that true??? pleas help me
thanks

Dear Fariba,

Regarding thermoforetic term, you have to use a UDF but coagulation effect is a lagrangian feature and you may model it in eulerian point of view. But about brownian effect, you don't need any UDF; the diffusion term of UDS equation has required effect.

Bests,

[fariba.j]

Originally Posted by Amir

Dear Fariba,

Regarding thermoforetic term, you have to use a UDF but coagulation effect is a lagrangian feature and you may model it in eulerian point of view. But about brownian effect, you don't need any UDF; the diffusion term of UDS equation has required effect.

Bests,

Dear Amir,
I agree with you,but I don't know, how I can perform thermophoretic with a udf to uds,through sourse term?! but source term must be constant,while my source term is a function.
also,uds is for single-phase,while I have a particle-laden flow(discrete particles in a countinous gas flow),in material panel,I have to only introduce gas(for example air) as material? I mustn't define two materil (a gas and a solid) in fluid catigory and define their properties???

cheers,

[Amir]

Originally Posted by fariba.j

how I can perform thermophoretic with a udf to uds,through sourse term?! but source term must be constant,while my source term is a function.

The source term can be a function of other parameters! Here this a function of temperature gradient and you can perform it with a simple UDF. (refer to UDF manual)

Originally Posted by fariba.j

also,uds is for single-phase,while I have a particle-laden flow(discrete particles in a countinous gas flow),in material panel,I have to only introduce gas(for example air) as material? I mustn't define two materil (a gas and a solid) in fluid catigory and define their properties???

You have one material if you want to use eulerian approach as you said before. In this methodology, you'll obtain particle concentration (UDS; a scalar) not the particle trajectories and the only particle-related data is diffusion coefficient which provided in base material panel.

[fariba.j]

my professor believe that for my problem, I have to spot one-phase, and calculate particle concentration with a uds,but I think I have to spot two-phase(fluid-solid) and use mixture multiphase model(i spot the same velocity for phases,so mixture model reduce to homogenous multiphase flow) and calculate particle concentration with a uds.which of us say correct?

[fariba.j]

[QUOTE=Amir;355710]The source term can be a function of other parameters! Here this a function of temperature gradient and you can perform it with a simple UDF. (refer to UDF manual
In sorce term help,say that in sorce term panel,from drop-list you can choose none,constant or udf for defining your source term.But there aren't udf option in drop-list(only none and constant),so I don't know, how I can define a non-constant term to uds through udf!

[Amir]

Originally Posted by fariba.j

my professor believe that for my problem, I have to spot one-phase, and calculate particle concentration with a uds,but I think I have to spot two-phase(fluid-solid) and use mixture multiphase model(i spot the same velocity for phases,so mixture model reduce to homogenous multiphase flow) and calculate particle concentration with a uds.which of us say correct?

I agree with your supervisor. Computing particle concentration doesn't need extra phase and can be easily handled via a UDS in a single phase.

Originally Posted by fariba.j

In sorce term help,say that in sorce term panel,from drop-list you can choose none,constant or udf for defining your source term.But there aren't udf option in drop-list(only none and constant),so I don't know, how I can define a non-constant term to uds through udf!

After loading a UDF for source term, you can see and choose UDF option in this panel.

Bests,

[fariba.j]

After loading a UDF for source term, you can see and choose UDF option in this panel.

Bests,[/QUOTE]


thank you very much,for your guidance. but my continous equation doesn't converge(I specified 1e-6 for residual)

[Maryam-A]

Hi there
I'm simulating nanofluid flow in microchannel, I want to use one transport equation for volume fraction. I wrote udf but I have problem
1- the error is : Label "n_uds" not found.
: function " internal_error " not found.
this is one part of my cod:
enum
{
alpha,
A,
B,
N_REQUIRED_UDS
};
DEFINE_ADJUST(alpha_adjust,d)
{
real Laplacian;
Thread *t;
cell_t c;
if(N_UDS<N_REQUIRED_UDS)
Internal_Error("not enough user-defined scalars allocated");

thread_loop_c(t,d)
{
begin_c_loop(c,t)
{
C_UDSI(c,t,1)=C_T_G(c,t)[0];
C_UDSI(c,t,2)=C_T_G(c,t)[1];
/*C_UDSI(c,t,3)=C_T_G(c,t)[2];*/
Laplacian=Laplacian+C_UDSI_G(c,t,1)[0]+C_UDSI_G(c,t,2)[1];
}
end_c_loop(c,t)
}
C_UDSI(c,t,1)=Laplacian;
}
As you see I used 3 uds, 1 for volume fraction, 2 others for calculation of temperature gradient and make Laplacian.
is it write?
2-another question is I used single phase, is it write?
I would appreciate if anyone can help me.