CFD Online Discussion Forums - FLUENT http://www.cfd-online.com/Forums/ en Wed, 08 Sep 2010 11:45:03 GMT vBulletin 60 http://www.cfd-online.com/Forums/images/misc/rss.jpg CFD Online Discussion Forums - FLUENT http://www.cfd-online.com/Forums/ local nusselt for heated channel http://www.cfd-online.com/Forums/fluent/79909-local-nusselt-heated-channel.html Wed, 08 Sep 2010 11:24:44 GMT hi everybody, I want to calculate local Nusselt for heated channel. I have a constant heat flow, how to calcul Twall and T ref for each point... hi everybody,

I want to calculate local Nusselt for heated channel.
I have a constant heat flow, how to calcul Twall and T ref for each point along the wall!

please i need your help

thank you ]]> FLUENT gina http://www.cfd-online.com/Forums/fluent/79909-local-nusselt-heated-channel.html ERROR: End AOA in airfoil table too small k 1 i 1 in Fluent 6.3 http://www.cfd-online.com/Forums/fluent/79906-error-end-aoa-airfoil-table-too-small-k-1-i-1-fluent-6-3-a.html Wed, 08 Sep 2010 10:53:39 GMT Hi everyone,

i am using fluent 6.3 and i'm trying in generating results for a 2 bladed helicopter having 2 sections. I have the sectional lift and drag arranged in the .dat files which is similar to the standara format used in the NACA 0015.

My AOA varies from -20 to 26 degrees.

When i run it on Fluent i seem to get this error no matter how much i change the format.

Does anyone have a idea on the matter?

Thanks ]]> FLUENT Asela http://www.cfd-online.com/Forums/fluent/79906-error-end-aoa-airfoil-table-too-small-k-1-i-1-fluent-6-3-a.html Velocity gradients from previous time step... http://www.cfd-online.com/Forums/fluent/79901-velocity-gradients-previous-time-step.html Wed, 08 Sep 2010 09:24:30 GMT Hi,

Maybe my previous thread wasn't clear enough.

I'm asking how can I access the values of velocity gradients from the previous time step...

Thanks
Mateus ]]> FLUENT mateus http://www.cfd-online.com/Forums/fluent/79901-velocity-gradients-previous-time-step.html Weld pool simulation of laser-hyrid welding http://www.cfd-online.com/Forums/fluent/79900-weld-pool-simulation-laser-hyrid-welding.html Wed, 08 Sep 2010 09:17:02 GMT Hi, My research goal is to simulate laser hybrid weld pool by using ANSYS Fluent. I dont have much idea about this kind of simulation. Is there... Hi,

My research goal is to simulate laser hybrid weld pool by using ANSYS Fluent. I dont have much idea about this kind of simulation. Is there any tutorial available for weld pool simulation so that I can start learning?

Regards
Minhaj ]]> FLUENT minhaj_iut http://www.cfd-online.com/Forums/fluent/79900-weld-pool-simulation-laser-hyrid-welding.html fluent version http://www.cfd-online.com/Forums/fluent/79894-fluent-version.html Wed, 08 Sep 2010 05:57:33 GMT Good Day, sir/madam , from next month onwards i am going to be handling a project on numerical study of v2-f turbulence model for impingement... Good Day,
sir/madam ,
from next month onwards i am going to be handling a project on numerical study of v2-f turbulence model for impingement of air flow over a flat plate, but i don't know which FLUENT version is suitable for me even i dont have more knowledge about FLUENT bcoz i m a M.tech student, and also ple let me know which meshing s/w is suitable for this project, which simulation techniques is helpfull for me.
ple reply as soon as possible
thanking you
 ]]> FLUENT jitendra http://www.cfd-online.com/Forums/fluent/79894-fluent-version.html what does mean NV_S and NVD in UDF. http://www.cfd-online.com/Forums/fluent/79893-what-does-mean-nv_s-nvd-udf.html Wed, 08 Sep 2010 04:18:00 GMT
Quote:
#include "udf.h"
DEFINE_GRID_MOTION(plate,domain,dt,time,dtime)
{
Thread *tf = DT_THREAD(dt);
face_t f;
Node *v;
real NV_VEC(omega), NV_VEC(axis), NV_VEC(dx);
real NV_VEC(origin), NV_VEC(rvec);
real sign;
int n;
/* set deforming flag on adjacent cell zone */
SET_DEFORMING_THREAD_FLAG(THREAD_T0(tf));
sign = -5.0 * sin (26.178 * time);
Message ("time = %f, omega = %f\n", time, sign);
NV_S(omega, =, 0.0);
NV_D(axis, =, 0.0, 1.0, 0.0);
NV_D(origin, =, 0.0, 0.0, 0.152);
begin_f_loop(f,tf)
{
f_node_loop(f,tf,n)
{
v = F_NODE(f,tf,n);
/* update node if x position is greater than 0.02
and that the current node has not been previously
visited when looping through previous faces */
if (NODE_X(v) > 0.020 && NODE_POS_NEED_UPDATE (v))
{
/* indicate that node position has been update
so that it’s not updated more than once */
NODE_POS_UPDATED(v);
omega[1] = sign * pow (NODE_X(v)/0.230, 0.5);
NV_VV(rvec, =, NODE_COORD(v), -, origin);
NV_CROSS(dx, omega, rvec);
NV_S(dx, *=, dtime);
NV_V(NODE_COORD(v), +=, dx);
}
}
}
end_f_loop(f,tf);
}
I don't know that means. I didn't find a whole day in google and UDF manual.

please explain to me.. ]]> FLUENT oilsok http://www.cfd-online.com/Forums/fluent/79893-what-does-mean-nv_s-nvd-udf.html Double layer Microchannel - Flow and Heat transfer http://www.cfd-online.com/Forums/fluent/79890-double-layer-microchannel-flow-heat-transfer.html Wed, 08 Sep 2010 00:04:12 GMT I am solving 3d flow and conjugate heat transfer in a double layered micro-channel. I am considering half of the channel due to symmetry. I have a... I am solving 3d flow and conjugate heat transfer in a double layered micro-channel. I am considering half of the channel due to symmetry. I have a velocity inlet for both the layers, and a fully developed conditions( both hydro dynamically and thermally) at the outlet, so an outflow at the outlet. I have coupled walls near the solid-fluid interface. I have constant heat flux at the bottom of the channel. Rest all are walls.

I am running a 3d steady, laminar case and the solution is not converging. The mass flow rate is being balanced. SO can anyone let me know where I am going wrong? ]]> FLUENT priyanka.asp http://www.cfd-online.com/Forums/fluent/79890-double-layer-microchannel-flow-heat-transfer.html Trouble with journal file reading wall boundary condition http://www.cfd-online.com/Forums/fluent/79884-trouble-journal-file-reading-wall-boundary-condition.html Tue, 07 Sep 2010 16:02:19 GMT Hello All, I have created a journal file to read in a 2D case. The file is breaking down when it gets to the place where it is reading the... Hello All,

I have created a journal file to read in a 2D case. The file is breaking down when it gets to the place where it is reading the boundary conditon. The error i am getting is:

no ; Shear Boundary Condition [shear-bc-noslip]: Change current value? [no]
no
Error: eval: unbound variable
Error Object: no
Invalid length

When do it from the command prompt in fluent, it does not return this error.

Any idea what is wrong?

Thanks in advance for the help.

James ]]> FLUENT jwillie2000 http://www.cfd-online.com/Forums/fluent/79884-trouble-journal-file-reading-wall-boundary-condition.html Two fluids at inlet http://www.cfd-online.com/Forums/fluent/79883-two-fluids-inlet.html Tue, 07 Sep 2010 15:53:32 GMT Hi, How to inlet two fluids at different fluids at a common inlet say into a mixing chamber??? Hi,

How to inlet two fluids at different fluids at a common inlet say into a mixing chamber??? ]]> FLUENT Haree http://www.cfd-online.com/Forums/fluent/79883-two-fluids-inlet.html How can I implement temperature jump boundary condition in microchannel walls? http://www.cfd-online.com/Forums/fluent/79869-how-can-i-implement-temperature-jump-boundary-condition-microchannel-walls.html Tue, 07 Sep 2010 10:07:10 GMT Hi, I want to apply slip velocity and temperature jump boundary condition to the walls of a two-dimensional channel in Fluent. I use your... Hi,

I want to apply slip velocity and temperature jump boundary condition to the walls of a two-dimensional channel in Fluent.
I use your report (IFTR reports). There is not any problem for slip boundary condition but the following errors appear when I apply temperature jump to the wall:


Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()




I'd be grateful if someone help me. ]]> FLUENT sima http://www.cfd-online.com/Forums/fluent/79869-how-can-i-implement-temperature-jump-boundary-condition-microchannel-walls.html How can I implement temperature jump boundary condition in microchannel walls? http://www.cfd-online.com/Forums/fluent/79868-how-can-i-implement-temperature-jump-boundary-condition-microchannel-walls.html Tue, 07 Sep 2010 10:06:10 GMT Hi everyone, I want to apply slip velocity and temperature jump boundary condition to the walls of a two-dimensional channel in Fluent. There... Hi everyone,

I want to apply slip velocity and temperature jump boundary condition to the walls of a two-dimensional channel in Fluent.
There is not any problem for slip boundary condition but the following errors appear when I apply temperature jump to the wall:


Error:
FLUENT received fatal signal (ACCESS_VIOLATION)
1. Note exact events leading to error.
2. Save case/data under new name.
3. Exit program and restart to continue.
4. Report error to your distributor.
Error Object: ()




I'd be grateful if help me. ]]> FLUENT sima http://www.cfd-online.com/Forums/fluent/79868-how-can-i-implement-temperature-jump-boundary-condition-microchannel-walls.html problem with heat flux in the wall http://www.cfd-online.com/Forums/fluent/79865-problem-heat-flux-wall.html Tue, 07 Sep 2010 08:52:54 GMT Hello I am modeling a plate fin heatsink in fluent,when i apply constant heat flux for example 200 w/m^2 to the base plate there is no heat... Hello
I am modeling a plate fin heatsink in fluent,when i apply constant heat flux for example 200 w/m^2 to the base plate there is no heat transfer between the solid heatsink and the fluid flow and there is no difference between inlet and outlet temperatures,but when instead of heat flux i apply "heat generation" to the base plate,in this case there is heat transfer between heatsink and fliud flow, and the temperature of inlet and outflow differs,do you have any idea what is the problem with heat flux?
Thanks ]]> FLUENT gholamghar http://www.cfd-online.com/Forums/fluent/79865-problem-heat-flux-wall.html Velocity gradient in previous timestep http://www.cfd-online.com/Forums/fluent/79863-velocity-gradient-previous-timestep.html Tue, 07 Sep 2010 08:47:19 GMT Hi, I need to write an UDF where velocity gradients in current and previous timestep are included. As far as I understand gradients from... Hi,

I need to write an UDF where velocity gradients in current and previous timestep are included.

As far as I understand gradients from previous timestep cannot be called directly (like for the current time - for example C_DUDX(c,t)). I guess the easiest way (the only way) is to use velocity from previous time step (C_U_M1(c,t)) and calculate the gradient... But I cannot find a macro for the cell size... and also what happens when I use unstructured mesh?
Where is it written how Fluent calculates the velocity gradient?

Thanks,
Mateus ]]> FLUENT mateus http://www.cfd-online.com/Forums/fluent/79863-velocity-gradient-previous-timestep.html air entrainment in fluent http://www.cfd-online.com/Forums/fluent/79858-air-entrainment-fluent.html Tue, 07 Sep 2010 06:38:16 GMT Hellow I want to model HYDRAULIC JUMP (including air entrainment) with FLUENT . Can fluent do This work. Hellow I want to model HYDRAULIC JUMP (including air entrainment) with FLUENT . Can fluent do This work. ]]> FLUENT hamedarshadi http://www.cfd-online.com/Forums/fluent/79858-air-entrainment-fluent.html Coloring of particles http://www.cfd-online.com/Forums/fluent/79857-coloring-particles.html Tue, 07 Sep 2010 06:37:58 GMT Hello

I have 5 spherical balls of different diameter being injected in the pipe But the color of all the balls are same when i click on "display" in the "particle tracks" with "particle variables color by particle diamter.

Could anyone please guide me how can i change the color of the balls with respect to diameter so that its easy to visulaize.

Thanks
Mohsin ]]> FLUENT Mohsin http://www.cfd-online.com/Forums/fluent/79857-coloring-particles.html