CFD Online Discussion Forums - STAR-CCM+ http://www.cfd-online.com/Forums/ en Thu, 09 Sep 2010 09:11:27 GMT vBulletin 60 http://www.cfd-online.com/Forums/images/misc/rss.jpg CFD Online Discussion Forums - STAR-CCM+ http://www.cfd-online.com/Forums/ Solver Error http://www.cfd-online.com/Forums/star-ccm/79929-solver-error.html Wed, 08 Sep 2010 17:31:04 GMT I have a simulation that works fine with I pick constant density as the physics model. But when I change it to real gas or ideal gas I get this... I have a simulation that works fine with I pick constant density as the physics model. But when I change it to real gas or ideal gas I get this error message:

Error:
A floating point exception has occurred: floating point exception [Divide by zero]. The specific cause cannot be identified. Please refer to the troubleshooting section of the user's guide

The other physic models I am picking are:
Space: Three Dimensional
Time: Steady
Material: Gas
Flow: Segregated Flow
Viscous Regime: Turbulent
Reynolds-Averaged Turbulence: K-Epsilon Turbulence



I am modeling 1.3 bars of helium going through a pipe-like environment. Please help me fix this, also does anyone have advice on what Reynolds-Average Turbulence model to use? Thanks in advance. ]]> STAR-CCM+ malfonso1286 http://www.cfd-online.com/Forums/star-ccm/79929-solver-error.html GT-Power - Star-CCM+ Coupling http://www.cfd-online.com/Forums/star-ccm/79907-gt-power-star-ccm-coupling.html Wed, 08 Sep 2010 10:59:11 GMT Hello,
I'm trying to couple GT-Power and Star-CCM+ (my versions are avaible for that) and I have no experience for that.
Has someone a tutorial about this topic ? Or can someone give me some tipps about this subject ?
Thank you in advance
Best regards ]]> STAR-CCM+ sheintz http://www.cfd-online.com/Forums/star-ccm/79907-gt-power-star-ccm-coupling.html Environment variable in linux http://www.cfd-online.com/Forums/star-ccm/79903-environment-variable-linux.html Wed, 08 Sep 2010 10:08:45 GMT :confused:When I install star-ccm+ successfully, it didn't work well, there is something wrong. someone said when star-ccm+ installed, I must set the environment variable, but i knew linux very little,could someone tell me how to set the environment variable? Thanks! ]]> STAR-CCM+ xinzhiyu2008 http://www.cfd-online.com/Forums/star-ccm/79903-environment-variable-linux.html Thresholds and field functions http://www.cfd-online.com/Forums/star-ccm/79895-thresholds-field-functions.html Wed, 08 Sep 2010 06:25:48 GMT I have been having some trouble recently with a model that has a threshold that is monitoring a gas flow. I have set the scenes up in a single core... I have been having some trouble recently with a model that has a threshold that is monitoring a gas flow. I have set the scenes up in a single core mode, and added a scalar threshold with a field function of "mass density of gas" and it runs and solves fine and i can export each time step as an image to watch the gas flow.
I have then tried to run this over a few more cores but when i go to open the scene it goes into a updating scene loop that it never gets out of. I can create other things like iso surfaces, and can plot the filed function in sections, and can open a scene and a a threshold, but it does not seem to work as a threshold with a field function.

Any ideas people?

thanks heaps ]]> STAR-CCM+ tobe http://www.cfd-online.com/Forums/star-ccm/79895-thresholds-field-functions.html star-ccm and linux http://www.cfd-online.com/Forums/star-ccm/79892-star-ccm-linux.html Wed, 08 Sep 2010 03:04:42 GMT I want to install the star-ccm in linux, but i don't know how to use the license, who can tell me the order.. how to start the lmgrd. and...if i install it successfully how can i start the software? i start studying the linux less than 2 days, help me ,thanks!! ]]> STAR-CCM+ xinzhiyu2008 http://www.cfd-online.com/Forums/star-ccm/79892-star-ccm-linux.html Black screen when importing geometry http://www.cfd-online.com/Forums/star-ccm/79877-black-screen-when-importing-geometry.html Tue, 07 Sep 2010 14:13:12 GMT Hi all. I would really appreciate some help on this. Ive created a 3D surface model using Autocad , ive exported it as STEP file, imported it... Hi all. I would really appreciate some help on this.

Ive created a 3D surface model using Autocad , ive exported it as STEP file, imported it into Star-Design, and then exorted it back to STAR CCM+.

However, after star ccm is done importing the cad, i cannot see the geometry in star ccm+.... all i see is a black screen. Is there an explanation as to why?

It seems that the program has read everything fine with no errors ..but cannot really see anything on geometry scene.

Thanks in advance.

Steve. ]]> STAR-CCM+ king_steve http://www.cfd-online.com/Forums/star-ccm/79877-black-screen-when-importing-geometry.html Problems with residuals oscillations http://www.cfd-online.com/Forums/star-ccm/79787-problems-residuals-oscillations.html Fri, 03 Sep 2010 15:04:11 GMT Hi everybody,
i'm using star-cmm+ 5.02.010 and i'm carrying on a simulation (steady model) concerning a cyclone separator, with two phases (air + dust) and segregated model.
boundary conditions: velocity inlet for the inlet tube, pressure outlet for the air outlet tube and wall (escape condition) for the dust outlet tube.

after 2000-3000 iterations ("lagrangian multiphase solver = frozen") the residulas start to oscillate and i cannot solve this problem. i tried to change the following parameters without positive effects:

- "velocity under-relaxation factor" from 0.7 to 0.45
- "pressure under-relaxation factor" from 0.4 to 0.1
- "K-Omega Turbulence under-relaxation factor" from 0.8 to 0.4
- "K-Omega Turbulent viscosity under-relaxation factor" from 1 to 0.5

I left these parameters this way and after this i also changed the following parameter (in the Physics model --> Segregated flow): the convection scheme from 2nd-order to 1-st order.
Then i've done 5000-6000 iterations and the residuals oscillations are very small and the mean values of residuals are much lower then before (i reached the convergence).
But i don't know if this change is correct...
After this convergence do i have to change again the order from 1st to 2nd? In other words, do i have to do 5000-6000 iterations with the 1st order and later other X iterations changing the order to 2nd?

And the parameters i changed (from the list i wrote before) are correct or is better left them as default?

thanks very much ]]> STAR-CCM+ spacecraft http://www.cfd-online.com/Forums/star-ccm/79787-problems-residuals-oscillations.html Error in the solver !!! what does this mean... http://www.cfd-online.com/Forums/star-ccm/79763-error-solver-what-does-mean.html Fri, 03 Sep 2010 07:07:14 GMT Hello

does anyone knows what is this error?

server error: a floating point exception has occured: floating point exception [invalid operation]. The specific cause cannot be identified. Potential causes may include : (a) solution divergence due to poor mesh quality, crude initiliazation, etc, or (b) errors in the user-defined code or field fuctions.


thanks ]]> STAR-CCM+ eleazar http://www.cfd-online.com/Forums/star-ccm/79763-error-solver-what-does-mean.html Boundary Condition Questions http://www.cfd-online.com/Forums/star-ccm/79758-boundary-condition-questions.html Thu, 02 Sep 2010 21:34:11 GMT I have just started using STAR-CCM+ and I am unsure how to set my boundary condition. I have a pipe-like chamber with a total for 4 inlets and 1... I have just started using STAR-CCM+ and I am unsure how to set my boundary condition. I have a pipe-like chamber with a total for 4 inlets and 1 outlet. Inside the chamber the pressure is supposed to be a constant 0.3 atm of helium. The outlet goes to a environment with zero pressure, a vacuum. The helium is sucked out of the chamber through the outlet and then is replaced by helium coming through the 4 inlets, keeping the pressure constant. What boundary condition should I be using? Do I need to set the reference pressure to 0.3 atm? ]]> STAR-CCM+ malfonso1286 http://www.cfd-online.com/Forums/star-ccm/79758-boundary-condition-questions.html Stream function http://www.cfd-online.com/Forums/star-ccm/79746-stream-function.html Thu, 02 Sep 2010 13:52:52 GMT Hi Star-CCM+ users,

I am modeling a 2D natural circulation flow. i obtain velocity field with no problem. Now, I'd like to get the value of the stream function at any point of interest. If I choose from the list the"Stream function" as Scalar field, then the value is zero. Apparently stream function values are not found (and stored) in my simulation.

How to "activate" this?

Thanks in advance. ]]> STAR-CCM+ MartiJ http://www.cfd-online.com/Forums/star-ccm/79746-stream-function.html Dfbi http://www.cfd-online.com/Forums/star-ccm/79737-dfbi.html Thu, 02 Sep 2010 06:58:08 GMT I v a problem with solving a DFBI case. I want too run a boat with thrust force in a domain. is that possible? I mean instead of setting a velocity...
I v a problem with solving a DFBI case. I want too run a boat with thrust force in a domain. is that possible? I mean instead of setting a velocity inlet i want to move the boat using a force acting on it. this case is very helpful to study maneuvering. I v already solved a simple case, but the results are not reliable for example free surface deformation is unreasonable and drag force plot is strange too, but as i expected the whole domain moves in the direction of applied force, and also boat motions seems to be rational. do you have any idea how to come up with this case?
thank you
]]> STAR-CCM+ Henry Arrigo http://www.cfd-online.com/Forums/star-ccm/79737-dfbi.html Axial Fan Model http://www.cfd-online.com/Forums/star-ccm/79615-axial-fan-model.html Sat, 28 Aug 2010 21:16:31 GMT Hi everyone, Has anyone used the axial fan modelling capabilities in star-ccm+? It works as a source term and I wonder if you have any... Hi everyone,

Has anyone used the axial fan modelling capabilities in star-ccm+?

It works as a source term and I wonder if you have any experience.

Cheers, ]]> STAR-CCM+ mardit http://www.cfd-online.com/Forums/star-ccm/79615-axial-fan-model.html interface type http://www.cfd-online.com/Forums/star-ccm/79600-interface-type.html Sat, 28 Aug 2010 00:03:18 GMT hi all, i am simulating a process where there is an interface between two bodies , a rotating tool and a moving sheet of metal, the tool rotates in... hi all, i am simulating a process where there is an interface between two bodies , a rotating tool and a moving sheet of metal, the tool rotates in addition to the interfaced region of the sheet, the sheet also translates linearly, what type of interface should I use ? is it in place of repeating? ]]> STAR-CCM+ ahmadbakri http://www.cfd-online.com/Forums/star-ccm/79600-interface-type.html Yacht Model Drag Analysis http://www.cfd-online.com/Forums/star-ccm/79571-yacht-model-drag-analysis.html Fri, 27 Aug 2010 09:19:06 GMT Hello everyone, I wonder if anyone has conducted sailing yacht drag analysis with multiphase option in STAR-CCM. I am comparing experimental... Hello everyone,

I wonder if anyone has conducted sailing yacht drag analysis with multiphase option in STAR-CCM. I am comparing experimental results of different size models with my analysis in STAR-CCM.

My major problem in all these analysis is being unable to find the right wall treatment. After finding the right size of cells for the free surface, wake regions and surrounding regions of the hull, keel and rudder -all being the same size-, I keep halving the size of cells on the surfaces of the hull, keel and rudder (to decrease the Y+ values) until the solution becomes grid independent. Note that during this approach, I adjust the time step in order to obtain a Courant Number of around 1-10.

With this approach, different size and different geometry models become grid independent at very different Y+ values. On a 6 meter model case the solution became grid independent at Y+ values of ~500, whereas on a 2.4 meter model as I decrease the Y+ from 400 towards 50, I keep deviating from the experimental results...

Does anyone have an idea about possible reasons for inconsistencies in the results? My expectation was to see that the results get reasonably closer to experimental results as I decrase Y+ towards ~50...

Thanks in advance,

Ziya ]]> STAR-CCM+ ziyasaydam http://www.cfd-online.com/Forums/star-ccm/79571-yacht-model-drag-analysis.html 6dof http://www.cfd-online.com/Forums/star-ccm/79562-6dof.html Fri, 27 Aug 2010 07:04:01 GMT Hi to all, I have little problem with 6DOF moving. I have cube in cube model and I followed star-ccm+ tutorial to set up my problem but there is... Hi to all,

I have little problem with 6DOF moving. I have cube in cube model and I followed star-ccm+ tutorial to set up my problem but there is one problem. As 6DOF object I choosed inner cube and set all needed properties.
When I run solver,region starts falling, not just cube which is selected as 6DOF.
Could you give me any suggestions?

Thank you very much.

B.

Edit: SOLVED ]]> STAR-CCM+ Birkov http://www.cfd-online.com/Forums/star-ccm/79562-6dof.html