Tips & Tricks - CFD-Post

Tech Tip – Transient Animation Improvements in CFD-Post

ANSYS CFD-Post is a state-of-the-art postprocessing tool used to visualize and quantify results from CFD simulations. At R17, transient flow variations are easier to animate using the new “Timestep Animation” option. This new capability uses ‘music-player’ style controls to play back transient results.

CFD-Post Animation graphical user interface

CFD-Post Animation graphical user interface

Some new user-interface options for Timestep Animation:

  • ‘Specify Range For Animation’ allows to trim the start/stop at specific timesteps instead of playing the entire animation.
  • ‘Advanced Frame Selection Controls’ allows to skip timesteps during the animation. This option is useful for speeding-up creation of animations from large results files.

 

 

 

 

 

 

 

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Tech Tip – Reverse Engineering Your Deformed Results in ANSYS

kaan-80x80The deformed geometry capability in ANSYS R17 is one of the most powerful and easy to use new features in the latest release of ANSYS. In addition to the new workflows that it enables, you can also easily reverse engineer your deformed results using ANSYS SpaceClaim. In this post I’ll show how to take your deformed geometry to another ANSYS analysis. Then I’ll show how you can use the powerful reverse engineering features in SpaceClaim to make your deformed results into a geometry again.

Deformed Geometry – Analysis to Analysis

Where previously you needed to create named selections and use scripts with intermediate MAPDL and FEModeler systems, now you can just drag and drop connections on the Workbench schematic:

DeformedGeometryAnalysisToAnalysis

A couple of notes:

  • For dynamic analysis that use the Linear Perturbation method, this happens behind the scenes on the mesh already. No need to apply this for the standard harmonic analysis.
  • If you want to use this parametrically, you will need to apply loads on the downstream analysis with APDL or loads that are compatible with nodal named selections. All other named selections and loads will be lost/unassigned when the deformed geometry is updated.
  • The shape but not any stress states are transferred. If stress states are desired, the INISTATE APDL command will be necessary.

Deformed Geometry – Analysis to Geometry

You are not limited to just sending deformed geometry to another analysis, you can also send it back to a geometry using tools that you probably already have. Here we will work with a metal forming test case, done with ANSYS Autodyn. See this workflow in the video below.

 

The first step is to right click on the desired geometry result and select Export -> STL

DeformedGeomContextMenu

The STL format is a faceted data format, which is not strictly compatible with the types of geometry that ANSYS and most CAD systems expect. You can think of it as a surface mesh of triangles around the geometry. It is not explicitly associated with a volume and if the quality of the STL file is poor, filling the mesh can be problematic. An STL surface mesh simply converted into a volume is a relatively inefficient way to represent geometry for ANSYS. Luckily we can do some reverse engineering in ANSYS SpaceClaim, a tool which you may already have.

Notice that our shell elements from ANSYS are represented as 3D in the exported deformed geometry. The STL file is brought in as a mesh body type. ANSYS SpaceClaim is used extensively in reverse engineering. We can see that we have a few options in the Insert -> Reverse Engineering section of the ribbon interface.

SCDMReverseEngineeringRibbon

We will be using the Skin Surface tool. This allows us to define surface bounds and control points to create a surface corresponding to a surface mesh region. The initial attempt is fairly imprecise:

SkinSurfaceFirst

What happened here is that the surface mesh fitted to both the top AND bottom sides of the thin body. The primary way to deal with this is to sample smaller, less complex areas of the surface. The Skin surface tool lends itself naturally to this workflow of creating patches of several different surfaces.

SkinSurfaceNext

See this video for more information on the reverse engineering features can capabilities of SpaceClaim.

Optionally we can also improve the quality of the mesh to better resolve the curvature using the Facets tab, enabled by an add-on license to SpaceClaim. It is used commonly in 3D printing applications and it has tools for working with dirtier meshes than what we will generally export from ANSYS.

FacestSmoothing

Once we have all of the surfaces fitted and created, ideally it will turn into a solid automatically. There will typically be precision issues, though, that keep the surfaces from forming an airtight volume. The Repair -> Solidify section has tools to help with this. After fixing some small gaps we have a solid geometry.

SolidifyRibbonAndSolid

Afterwards it is good practice to check the Deviation of how well the geometry matches the source mesh. We can do this in the Measure -> Deviation tool. Notice how the carefully created top surface patches have better deviation than the quick and dirty bottom surface patches.

DeviationResult

Hopefully you’ve found that helpful!

If this was useful to you and you’d like to hear other ways to speed up your simulations contact us or subscribe to our newsletter below:

 

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Supercharge your system simulations with the ANSYS MATLAB Toolbox

kaan-80x80One of the most exciting features in the latest release is something that’s not getting much publicity: running MAPDL (or ANSYS Classic) as a headless server. Okay, I can see why people may not be too excited by that but it allows you to run Mechanical APDL with whatever user interface you want, for example – MATLAB. With the MATLAB toolbox you can to run ANSYS, the number one FEA solver in the world, like any other module in MATLAB. This opens up all kinds of possibilities for co-simulation with ANSYS and MATLAB, taking your integrative and system simulations to the next level.

This is not just a more sophisticated way to send batch files to Ansys MAPDL, you can send commands and receive output from a running Ansys FEA solver:

>> mapdl.executeCommandToString('asel,s,mat,,6')

ans =

SELECT       FOR ITEM=MAT  COMPONENT=\n  IN RANGE         6 TO          6 STEP          1\n\n

You can interrogate parameters:

>> str = mapdl.executeCommandToString('*get,max_x,node,,mxloc,x')

str =

*GET MAX_X FROM NODE ITEM=MXLO X VALUE= 500.000000

>> exp = 'VALUE= ([^\s]+)'

exp =

VALUE= ([^\s]+)

>> m = regexp(char(str),exp,'tokens')

m =

{1x1 cell}

>> str2double(char(m{:}))

ans =

500

You can execute commands using Matlab control logic:

 >> loads

loads = 

1x2 struct array with fields:

 cmsel
 val

>> for elem = loads
mapdl.executeCommandToString(strcat('d,', elem.cmsel,',uy,',num2str(elem.val)))

ans =

SPECIFIED CONSTRAINT UY FOR PICKED NODES\n REAL= 300.000000 IMAG= 0.00000000

ans =

SPECIFIED CONSTRAINT UY FOR PICKED NODES\n REAL= 0.00000000 IMAG= 0.00000000

Writing data files is still handled by batch files but MATLAB easily reads and works with comma separated data files:

>> type('to_outf.inp')

*cfopen,outputs,csv
*vwrite,
("plwk_top, plwk_bot")
*vwrite,plwkData(1,1), plwkData(1,2)
(E16.8, "," E16.8)
*cfclos

>> mapdl.executeCommand('/inp,to_outf,inp')

>> tab = readtable('outputs.csv')

tab =

plwk_top plwk_bot
________ ________

0.013099 0.010709
0.025962 0.021216

And of course there are all the plotting and visualization functionality that you are used to:

bar3(table2array(tab))

MatlabFigure

You can similarly interface with Workbench and Fluent with this toolbox.

We are pleased to make this ANSYS Matlab Toolbox available early for our customers (please log in):

Download ANSYS Matlab Toolbox

If you are not a customer, we can offer this as premium content:


 

What is new in ANSYS Maxwell R17?

mehrnooshMaxwell & Simplorer Integration to ANSYS Electronics Desktop

The ANSYS Electronics Desktop environment provides a common user interface, model entry and setup, simulation control, and post processing in a single framework for Electromagnetic (EM) simulation applications. In ANSYS R17, Maxwell and Simplorer are added to ANSYS Electronics Desktop. The new ANSYS Electronics Desktop houses Maxwell, Maxwell Circuit, Simplorer, HFSS, Designer, and Q3D Extractor.

ANSYS Electronics Desktop (AEDT) R17

ANSYS Electronics Desktop (AEDT) R17

Key Features

Here are some key features of new ANSYS Electronics Desktop: 

• One desktop application handles multiple design types ‘EM configuration’ available under Tools> Options > General Options> General> User Interface (It includes Simplorer, Maxwell, Maxwell circuit Editor, RMxprt, Q3D, HFSS, Designer)
• Streamlines coupled workflows between systems/circuits and 3D
• Pre-defined Simplorer configuration preserves standalone look & feel
• Electronics Desktop products link to ANSYS Workbench for full multiphysics simulation and product optimization under real-world physical conditions.

 

 

 

By Mehrnoosh Khabiri


 

 

Tech Tip: What is new in ANSYS HFSS R17

Modelithics CLR Library for ANSYS Electronics Desktop/HFSS

Modelithics models are now compatible with ANSYS Electronics Desktop and HFSS circuit design. The Modelithics CLR Library for ANSYS HFSS improves the accuracy level of RF/Microwave electronic design. Once, the Modelithics CLR Library is installed into the ANSYS Electronics Desktop under the Component Libraries, designers can access the high accuracy simulation models by Modelithics from within the ANSYS HFSS design environment.

Modelithics

Modelithics CLR Library can be imported and solved with HFSS accurate EM co-simulation

The Modelithics CLR library contains Resistors, Inductors and Capacitors from the leading and popular vendors. The Modelithics models are measurement-based, scalable, statistical analysis capable and well-documented which make ANSYS HFSS EM simulation more accurate and valuable. The Modelithics models enhance ANSYS HFSS Electromagnetic (EM) co-simulation.

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