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

 

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

 

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

Converting Crank Angle to Time

EnSight’s transient capability, in particular the Pathline capability for time integrated streamlines relies on a consistent set of units. The time specified in the EnSight Case Format must match the units of time in the velocity field (distance/time). In older versions of ConvergeCFD, the velocity was written out as m/s, while the time was written out in crank angle. In this situation, the Pathline calculation routine will not correctly, as the units are not consistent. I’ve written a short quick little tool that converts the Crank Angle information to Time.

This little tool has the following attributes:
a. It sits in your UserDefinedTools area (so you don’t loose it), and you have a little single click icon to execute it.
b. It asks you for your Engine Speed in RPM, and the Case file containing Crank Angle
c. It moves the Crank Angle data over into its own separate file, so that user still has access to it through EnSight.
d. It modifies the .case file to include the above new crank angle file, and correctly writes time in the time values section.
e. It then asks you if you’d like to automatically load in this new .case file…

Bing…
You now have time correctly in there.
You also have Crank Angle as another Constant that you create a label with, dial, gauge, or calculate with automatically.

So, there is a video tutorial (~ 4 minutes) on setup and using this routine :

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

And the little routine can be downloaded from here:

 

http://www.ceisoftware.com/wp-content/uploads/screencasts/crank_angle_conversion/Convergent.zip
(updated 25-Sept-2012 to no longer require that the Case file be EnSight Gold (will work on non-Gold files too)

Let me know if you have any questions or problems.