Create Triangle Mesh

If you are faced with the problem that you have a hole in a surface EnSight has no powerful tool to fill it. Think about the radiator grille of a car. If one has the request to create a clip plane within the grille geometry to calculate the flow for example, the plane tool wont help in most cases as it’s rectangular and radiator grills are often not rectangular.

This tool can create a triangle meshes within a closed spline. If you campare the result with the meshing of a point part it has two big advantages:

1. The mesh elements are connected

2. Point parts along splines are meshed with one row of triangles. Here we have multiple rows. This enables calculation and coloring on the new mesh.

The spline geometry should be circular or elliptic and as flat as possible. Convex or concave geometries might cause problems. If the geometry is elliptic the first spline point should be at a pointed area (Think about the two ends of an egg). The scipt can use an existing spline or you can create a new one. If you select the option new spline, the GUI becomes interactive. Just click along the surface with the left mouse button and check how the spline points get created. There’s a control field of the current number of splines in the script GUI. If you want to get rid of one or more spline points, just use the delete button within the GUI. The spline can be open. The code will create a final spline point to close it. This will be done on existing splines and on new splines. Furthermore you can map an existing fluid variable to the new surface.

When the create button was pressed EnSight will create a new case and geometry file in the current working directory. These files are loaded as an additional case

 

 

 

 

 

 

 

The attached script is a stand alone tool. You can run it via File > Command > Play. Just contact me if you want to add it to your user tools.

triangle_mesh_2013_04_07

Dynamic Range Plotter

Suppose that you have a transient domain, where you have some information at a high temporal frequency, but your time domain is relatively large. If you make a default plotter, the temporal range is too large to see the high frequency information. But, if you zoom in the time range, you are “fixed” to a particular time. Suppose you’d like to see both the higher frequency information, but also the whole time domain?

Python to the rescue again. Using Python, we can dynamically adjust the time range of the graph at each timestep… and thus create a plotter with a relatively small time “window”, but that window moves with the current timestep, so that you can see the whole time domain.

Here is a short example of what such a “dyanmic range plotter” would look like:

dynamic_range_plotter

Here is a short tutorial on using this python tool:

http://www.ceisoftware.com/wp-content/uploads/screencasts/dynamic_range_plotter/dynamic_range_plotter.html

And here is the tool itself:

dynamic range plotter python

In-Cylinder Tools

In-Cylinder Engine (ICE) simulations often contain specialized requirements for analysis. EnSight’s Python tool capability allows users to develop their own custom operations to fulfill the requirements of the analysis. I have written an initial set of tools here called “In-Cylinder Tools”, which can be installed as UserDefinedTools in EnSight 10

In this set of tools, we have the following:

1. Calculate Swirl. This routine takes the currently selected parent part(s) (typically the fluid domain of the cylinder), and calculates Swirl Velocity based about the Z axis. Using the parent part, it also calculates an Constant Variable which is the Spatial Mean of Swirl, so that you could easily create a plot vs. time for the average swirl.

 

 

 

2. Calculate Tumble. This routine takes the currently selected parent part(s) (typically the fluid domain of the cylinder), and calculates a tumble velocity, using the current average height of the parent part. The routine automatically works through time to determine this tumble velocity using the new center reference point at each timestep, and creates a graph of tumble vs time.

 

 

 

3. Crank Angle Conversion tool. This converts an EnSight .case file which has been setup with Analysis_Time specified as degrees crank angle, and converts this to Analysis_Time in seconds (user provides RPM). This allows EnSight to compute Pathlines correctly, as all of the constituent variables have consistent units.

4. Spray.out reader. For users of Converge, this tool will read in the Spray.out file information into a series of queries that you can then automatically plot. This reader will also read other Converge .out files which confirm to the save format.

 

 

 

 

 

5. Particle Distribution Function. This routine operates on the Measured Data within EnSight, to determine a mass-based distribution of any measured data variable (like radius or temperature) within the time domain. Please refer to this previous Python Exchange article for further information on the intended uses and application of this routine. Previous article.

 

 

 

Please download these tools from the link below. Unzip the file, and place the directory into your .ensight100/extensions/user_defined/Tools/ directory, and restart EnSight. You should then see a new tool folder in your UserDefinedTools area with the above tools.

Should you require any assistance with the tools or modification of them to suit your particular needs, please do not hesitate to contact CEI.

Click here to download In_Cylinder_Tools

 

Importing Converge .out files

The Converge Solver exports out additional quantitative information into various “*.out” files. The information contained within these .out files can be very useful in visualizing along with the fluid domain in EnSight, to quantify against other extracted values in EnSight, qualitative comparison, or just to easily visualize versus time in EnSight.

This very small/short routine was developed to work on the spray.out file which contains information regarding the spray computed by the solver (injection pressure, injected mass, spray penetration, etc). The routine reads the .out file, along with the user specified engine RPM (to calculate time in seconds), and places all of the values from the .out file into EnSight Queries.

The User Defined Tool should appear as :

The user simply needs to specify the Converge .out file, along with the Engine RPM, so that the routine can correctly tie the query with time.

Once executed, you should see a number of additional queries within EnSight. The name of the Query is taken from the .out file, along with the units. Each query is associated with “Time” in seconds, and should therefore play correctly and appropriately within EnSight, as well as synchronizing with the timesteps of the main dataset.

The resulting Queries can easily be plotted with the Right Mouse Button, or drag/drop onto current plotters. Query-on-query operations can also be performed to further inspect rate of change, comparisons (differences between queries).

You can download the current User Defined Tool here. Once downloaded, unzip the file, and place the contents into your .ensight100/extensions/user_defined/Tools/ directory, and restart EnSight.

Click here to download Converge .out file reader

Particle Distribution Analysis

As a follow on to the Probability Density/Distribution Function for the continuous phase domain (link here), I have created a close cousin of this routine which works on Discrete Particles to determine a Particle Distribution of the Discrete Phase.

This routine was written with the intended use for Spray Distribution in an In-Cylinder model, and built according to the typical variables and techniques used for this modeling scheme. It is common to determine and understand what the distribution of the particular spray is within the domain over time (mass distribution vs. radius).  This routine asks the user for a variable to base the Distribution on (in this case droplet radius). The routine breaks this value down into N number of “bins” (in this case 20). For each bin, the routine calculates the total mass of the spray in that bin, and reports back out a distribution. The routine then walks the transient domain to collect this information over time, and generate extracted information vs. time.

In order to base the total in each bin on Mass, the user must prescribe three items : a) the droplet radius, b) the droplet density, and c) the number of droplet per parcel. In this instance, the actual Discrete/Particle data in EnSight represents one parcel of spray (all with the same physical properties).  Therefore, the mass is represented as (number_drop_parcel)*(particle_density)*(4/3*pi*r^3).

The GUI input for this routine is similar to the previous PDF macro for the continuous phase, with the addition of variable prescription needed for the mass calculation.

Based on this range, it then divides the volume into N number of IsoVolumes (number of bins) based on this variable range. The routine then determines the mass of the spray which is contained within each of these variable constrained ranges. The result is placed into a query register and automatically plotted on the screen.

The Tool presents the user with the simple Window to select the variable, and number of bins (or bars) for the distribution function, along with the three items needed to calculate the mass of the spray (radius, density, parcel count)

 

After executing, you will then get a graph of distribution of the variable within the parent part(s) selected.

The values on the graph should always sum to the total mass of spray in the domain.

Note: As users increase the number of bars( or bins) for the graph, the shape of the curve will increase in resolution, although values on the Y-axis of the graph will adjust.

This Tool can be downloaded from the link below. Please unzip the file and place both the Python Script and Icon PNG file into your UserDefinedTools area and restart EnSight. You should see a “PDF Particle Graph” icon available in your UDT area, and you can double click to execute.

 

 Video Tutorial:

Please view this video tutorial for a detailed walk through of using this tool for Spray Analysis.

Screencast Tutorial

Download:
Please use the following link to download the UserDefinedTool:

Click here to download Particle Distribution Tool

 

Gamma Uniformity Index

The Gamma Uniformity Index is a measure of flow uniformity on a clip plane.

It is the normalized RMS of the difference between the local velocity and the spatial mean of the velocity integrated over the area of the clip plane.  See the attached equation.

Gamma Uniformity Equation

Equation for Gamma Uniformity

Attached is a demonstration of EnSight Python for calculating the Gamma Uniformity Index. This is only intended as a prototype demonstration script for calculating this variable.

Directions for use: make a clip plane in your flow. Select the clip plane part.  If your velocity variable is different than ‘VELOCITY’ then you will have to edit this .py file to the correct variable name. Now run this script. You will have several intermediate variables calculated, but the gamma uniformity index is a constant named gam_uniform.

gamma_uniformity_index.py

 

Transient STL File Conversion

Do you have a series of STL files which represent moving geometry? If this geometric motion is simple (constant rotation, or translation), you can utilize the “Rigid Body Motion” capability already in EnSight. However, what if the motion is complex, or if the STL surfaces change from timestep to timestep? The native STL file reader in EnSight expects steady state STL file information (either a single STL file, or multiple STL files via .xct; but still only for a single timestep).

A short Python routine can be used here to actually help out. This python routine takes a series of STL files, and assumes that they are part of a transient sequence, with one STL file per timestep. The Python routine converts the STL information into EnSight Case Gold format files, with multiple .geo files, allowing you to view your STL information in a transient nature. This routine can be further modified and customized to suit your needs, file conventions, or time information (since no time information is explicitly available within the .stl file).

Please feel free to contact CEI, or the author of the routine (kevin@ceisoftware.com) for further customization or questions.

To download this example Python utility, please click on the link below, and place into your User Defined Tools area.

Click here to download Multiple Transient STL Conversion Tool

Current Version : 1.0 (11-January-2013)

Current Limitations/Assumptions:

a. A series of ASCII stl files all with ‘.stl’ extension
b. Will convert and assume ALL “*.stl” files in the directory are to be converted.
c. All STL files have the same number of parts (but can change triangles from timestep to timestep)
d. Since there is no Time information with STL, will force Time 0 = 0.0 seconds, Time 1 = 1.0 seconds, etc
If user needs other time information, just change the time values in the .case file
e. STL files are all triangles (no quads)

Help Documentation can be found here : https://sites.google.com/a/ensight.com/user_defined_tools/transient_stl_translation

Measure Distance & Size

EnSight has no really handy capability to measure the size of a selected part or the distance between two points although all necessary information is existig. I was asked several times for a simple click solution. Well, here it comes. Attached are two Python codes zipped to a complete directory. Both scripts include a dynamical GUI which enables a very handy usage.

The size measurement tool:

Start the routine and just select one ore more parts from the part list or directly from the graphical area – that’s all. The GUI of the code will update immediately so you will get the desired information without more steps.

 

 

 

 

 

 

 

 

The distance measurement tool:

Start the routine and choose the measurement mode. Now just click on the first surface point. The GUI will update at once and asks you to select the second surface point. Once again the GUI will update and tell you the distance betwee the two points. Both points are connected with the line tool now. You can continue picking surface points as long as the GUI is active. If you are finished, just quit the GUI and the line tool will disappear.

 

 

 

 

 

 

 

 

Both routines are included in a complete user defined tool directory. Download the file, unzip it and copy the whole directory to this path (If the path does not exist you’ll have to create it):

$HOMEDRIVE/$HOMEPATH/.ensight100/extensions/user_defined

 

Please contact me at david@ceisoftware.com if you have any problems.

david

CEI_GMBH_TOOLS

LIGGGHTS and STL Transient Conversion Routine

liggghtsDo you have LIGGGHTS data that you’d like to visualize, analyze, or communicate? Do you have similar DEM (Discrete Element Model) type of data? EnSight can used easily to analyze, visualize, and communicate the results from a LIGGGHTS solution. In this particular situation, the user has both LIGGGHTS dataset for each timestep, along with STL data for each timestep which represents the moving geometry. This python routine converts both the LIGGGHTS data file as well as the STL data into EnSight format, allowing you to visualize both the moving geometry and particles at the same time, but also utilize the analysis capabilities within EnSight to quantify the discrete particle solution for such things as mass, center of gravity, particles & mass within a particular geometric region, amount of particles leaving the domain vs. time, etc.

Please visit this site for the up-to-date help and version information regarding this Conversion Routine:

https://sites.google.com/a/ensight.com/user_defined_tools/liggghts-translation

The current release of this tool (version 1.6; 04-Dec-2012) can be downloaded with the following link. Simply place both files into your User Defined Tools directory, re-launch EnSight and start to visualize, analyze, and communicate your LIGGGHTS data within EnSight.

Click here to Download new version 1.6 of LIGGGHTS Conversion Tool

Vector length legend for vector arrows

This script requires some effort from the user and if used incorrectly it could lead to wrong or misleading information.

One of the EnSight created part types is a “Vector Arrow” part. The length of these arrows can be in proportional to the magnitude of the vector used to create them (the arrows can also be set to have uniform length). So the length of the arrows has definite meaning, but there is no ‘legend’ like the color palette legend which indicates what the length of a vector arrow means.

This script can create such a legend semi-automatically, but the legend is only accurate in certain situations. Since the arrows and the legend are in a 3D space, the direction the arrows are viewed from will affect how large the arrows appear. So I recommend using this legend only in certain situations such as:

  1. When all the arrows lay in a 2D plane, and they are viewed orthogonally with perspective view turned off (orthographic view mode)
  2. When the viewer can rotate the view, and therefore gauge the 3D scene and have an intuitive feeling about the distortion in size due to the viewer’s perspective

Example: The arrow length shows velocity while color indicates temperature.

The script performs a few simple steps:

  1. Create a single node using a point part
  2. Create a vector variable of unit magnitude on the node using MakeScalNode and MakeVect
  3. Create a vector arrow part on this node using this vector variable

The script will prompt you for the location and direction of the arrow. If desired, the location of the arrow can be changed by editing the point part. After the script runs the user should do two things:

  1. Adjust the arrow length by changing the scale factor of the Vector Arrow Legend part
  2. Create a text annotation indicating the meaning of the length of the reference arrow

One must be careful when scaling the legend arrow so that it represents the correct value. One could follow these steps:

  1. Adjust the scale factor of your vector arrow part(s) (not the legend part) to get the desired vector lengths. Call the scale factor “A”.
  2. Choose a vector value that you want the legend to represent, call this value “B”
  3. A * B = C, C is the scale factor you should use for the Vector Arrow Legend part (since the original vector magnitude is one). Now the legend arrow should be the same length in 3D space as an arrow that has vector value B.
  4. The text annotation should use the value B

Download the script. vector_legend.py

If you like the idea of a vector arrow length legend and would like to see it added as a standard feature of EnSight you can vote for it and other features at ideas.ceisoftware.com. Link to the arrow legend request