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Old   March 12, 2004, 08:20
Default Dynamic Mesh UDF
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Dynamic Meshing UDF's

I have done the tutorial 11.

My problems are: #1 To use the two following Sample Examples of Dynamic Meshing as mentioned in the documentation.

How can this be done? Is there any specific case for which these are being made? I have been able to build the UDF file for a simple grid with a bar being placed in flow but when I build it I get the message: -------------------------------------- " 1 file(s) copied. (system "move user_nt.udf libudf\ntx86\2d")0 (system "copy C:\FLUENT.INC\fluent6.1\src\makefile_nt.udf libudf\ntx86\2d\makefile") 1 file(s) copied. 0 (chdir "libudf")() (chdir "ntx86\2d")() Def_Grid_Geom.c # Generating udf_names.c because of makefile Def_Grid_Geom.obj

Done." -------------------------------------- And when I load it I get the message:

-------------------------------------- "Opening library "libudf"... Error: open_udf_library: The system cannot find the file specified.

Error Object: () " -------------------------------------- #2 The documentation of UDF does't give much help on writing UDF's except you tend to know what Define Macro are to be used, but making a UDF on a physical problem isn't well explained. Anyone having any guidelines?



The DEFINE_GEOM macro is used to define the geometry of a deforming zone. By default, FLUENT provides a mechanism for defining node motion along a planar or cylindrical surface. When FLUENT updates a node on a deforming zone (e.g., through spring-based smoothing or after local face re-meshing) the node is ``repositioned'' by calling the DEFINE_GEOM UDF. Note that UDFs that are defined using DEFINE_GEOM can only be executed as compiled UDFs.

The following UDF, named parabola, is executed as a compiled UDF.



By default, FLUENT updates the node positions on a dynamic zone by applying the solid-body motion equation. This implies that there is no relative motion between the nodes on the dynamic zone. However, if you need to control the motion of each node independently, then you can use a grid motion UDF. For a DEFINE_GRID_MOTION UDF, you can update the position of each node based on, for example, the deflection due to fluid-structure interaction.

#3 Has anyone had any experience of studying an oscilating airfoil with some frequency in Fluent using UDF? I am unable to get hold of the UDF business but it seems a very promising feature of Fluent.

Any comments and suggestion in these context would be appreciated.

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Old   December 2, 2009, 01:27
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Saeed Abbasi
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when you recieve this: "Opening library "libudf"... Error: open_udf_library
you must do this:
Run the Vcvars32.bat file in the ..\BIN directory found in the installed directory under ..\MSDEV or ..\DevStudio\VC. This file contains the environment variables required to run build tools from a command prompt.
and run Fluent from visual c++ command prompt
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