get "nan" on energy is iterated from converged cold-flow |
| The basic procedure for underhood case is:
1. activate SKE, DO, and Energy models 2. setup boundary conditions for flow, temperature, and radiation in serial solver (includes turning on planar... |
Cell Wall Distance in UDF: C_WALL_DIST, Fill_Cell_Wall_Distance, don't always work. |
| The cell wall distance is needed in a UDF for a laminar case.
Here, the default tools in FLUENT's UDF interface (like C_WALL_DIST(c,t)) don't work, because FLUENT doesn't calculated... |
FLUENT 6 - DEFINE_VECTOR_EXCHANGE_PROPERTY example |
| The use of DEFINE_VECTOR_EXCHANGE_PROPERTY is difficult, because the velocities that are needed for the calculation of the drag coefficient are not in the data fields they are supposed to be. At... |
Change from perspective to orthographic |
| if you want to change the default camera setting from perspective to orthographic ...
If you want to change the default setting for the camera from perspective to orthographic, here is what you... |
Fluent Inc Product - Windows Startup Error: The name specified is not recognized as an internal or external command, operable program or batch file. |
| The environment variables are not set and the operating system cannot find the appropriate .exe file it needs to run the program.
Resolution: Set your environment variables. Exit out of the... |
FLUENT - Possible cause and available workarounds for the "File #f not found" error when loading an XY plot file into FLUENT on the Windows platform |
| This behavior is specific to Windows 2000. Attempting to load and plot a file in the File XY Plot panel (in the GUI select Plot...File) without a .xy extension in its name causes an error dialog... |
FLUENT - Two common errors when using the planar conduction model (floating point exception or MPI error) and tips to address the underlying issues |
| Most of the issues with planar conduction in parallel mode are not actually due to parallel.
There are two other possible causes: I) If one gets floating point exception in serial mode, then one... |
FLUENT V6 - how to workaround the "invalid window id" error when you have 20 or more monitors defined with your run |
| If you define 20 or more monitors in your FLUENT run, you may see a "Invalid Window ID" error when you begin the calculation.
The problem lies in a limit of 20 windows that can be opened from... |
ANSYS Fluent: Best practices for surface tension dominated flows to reduce the spurious currents at the interface |
| 1. Patch with some diffused interface: Increase/decrease the height of liquid layer a bit, so that it cuts the cell by half, set the rpvar (rpsetvar 'patch/vof? #t). This is for better... |
POLYFLOW - velocity distribution is not rectilinear in a single Poiseuille flow when the mini-element is used. What is happening? |
| First of all, if non-linearities are involved, such as shear-rate dependence viscosity, it is always a good idea to check the convergence.
Next, when the mini-element with linear pressure... |
Is it possible to save custom variables so they are loaded into any CFD Post session? |
| Yes it is possible.
In your current CFD-Post session, define expressions and make sure they are working. You can save this State File for further use. Then delete all the contours, isosurfaces,... |
In POLYDATA - How can I define a periodic boundary conditions based on flow rate for viscoelastic flow? |
| This can be done by editing the data file.
Remove the SOLVER defined for the calculation of inflow boundary conditions, and add a problem '53' (2D) or '54' (3D) to the main... |
How to provide boundary conditions in Fluent when only total pressure drop is known? |
| Pressure inlet is formulated with total pressure and pressure outlet with static pressure.
You cannot directly provide total pressure drop as a boundary condition. A UDF example is provided for... |
Is it possible to modify the loss coefficient in the outlet-vent boundary condition via UDF? |
| No, it is not possible via UDF.
BUT, a scheme routine enables to automatically modify the coefficient depending on the average pressure on postprocessing zone. Please find the a description and... |
I would like to add a pressure inlet to a problem, where the boundary condition pressure is specified as a function of time. This is for a transient internal flow problem. Would you happen to have a simple example of this? |
| Transient Boundary Conditions
There are two ways you can specify transient boundary conditions: 1. transient profile with a format similar to the standard boundary profiles described in Section... |
What is the use of the normal force or flow rate when defining a periodic boundary condition in POLYFLOW? |
| When the periodic boundary condition involves a rotation only, there is formally no pressure difference between the source and target sides. The main reason is that one comes back to the source... |
what is the field variable "Absolute Pressure" in FLUENT? Is it static or total pressure? |
| It is Absolute Static Pressure.
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How do I change the zone type from wall to a pressure outlet in FLUENT? |
| This can be done in one of two ways:
1) In GUI (Graphical User Interface) Click on the zone whose type you want to change under "Boundary Conditions". Select the type "pressure outlet"... |
How to check for the existence of a RP-variable from within a UDF in FLUENT ? |
| To do the check, you can use the following routine, e.g. checking for 'pressure/relax' and 'pressure/relay':
#include "udf.h" DEFINE_ON_DEMAND(testrp) { CX_Message("RP Variable... |
VOF simulation diverges with the error message 'Global courant number is greater than 250.The velocity field is probably diverging' |
| Mesh Requirements:
If volume mesh contains tetrahedral elements, use double precision with node based gradient option (Spatial Discretization). Create uniform mesh. In regions where the mesh is... |
Are there any tips and tricks to aid convergence in periodic flow problems with specified mass flow rates in FLUENT? |
| If you are experiencing convergence difficulties while running a case with periodic boundaries and a specified mass flow rate, these are a few things you can try to improve the convergence... |
Why does my simulation predict unrealistic droplet evaporation rates? |
| Many users setup a droplet evaporation case in FLUENT and use default settings for material properties for the droplet. This is not correct as those are just placeholders. It is important to note... |
How do I enter hydrostatic head in ANSYS FLUENT? |
| When gravitational acceleration is activated in the Operating Conditions dialog box (accessed from the Boundary Conditions task page), the pressure field (including all pressure inputs) will... |
How can I monitor forces during my simulation using Newtons instead of dimensionless coefficients in FLUENT? |
| FLUENT always monitors forces using dimensionless coefficients. These are defined as
Coefficient = Force/(0.5ρV2A) (1) Where Force = Viscous + Pressure Force (on selected boundaries) ρ =... |
How can we achieve target thrust at a mass-flow-inlet boundary?
|
| For external aero applications involving the modeling of a full aircraft with engine and pylon, client typically knows the massflow rate incoming to the engine fan inlet and also the thrust... |