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Socrates…not a name that comes up in everyday conversation.  Yet, as CAE practitioners, let me propose that we apply the Socratic method every time we analyze our simulation results.  The Socratic method, or elenchus, “is a form of cooperative argumentative dialogue between individuals, based on asking and answering questions to stimulate critical thinking and to illuminate ideas and underlying presumptions(from Wikipedia).  So, who is having this dialogue?  Perhaps we could consider the numerical simulation to be our teacher in this exchange.  True to the Socratic method then, the better your questions are, the more you learn.  What does this have to do with DataFocus? In short, our latest enhancement, Data Focus, gives you an unprecedented way to ask your teacher (the simulation) really good questions and get great answers.

When reviewing simulation results, we commonly reduce informational detail, narrowing our focus, to get a better understanding of what is happening.  In the example below, we see four illustrations, all depicting flame temperature. 

At left, the flame is colored by temperature, in full detail.  Let’s say we want to focus on where the temperature in the flame is high.  We could clip the temperature scalar field at the displayer level, shown second from left (the minimum temperature is set to 1500K).  In this illustration however, we’ve lost some of the context – the complete flame structure is less clear and the colormap is re-scaled to fit the modified temperature extents.  By applying a Data Focus object, shown in the illustration second from right, we highlight the part of the flame above our minimum target temperature of 1500K.  The original colormap-to-temperature mapping is preserved and values below our minimum have the color hue removed, thereby retaining the visual context of the flame.  But, we can take this one step further and ask a deeper question: What part of the flame is above 1500K and has a mixture fraction, f, greater than 0.5?  The result of this Data Focus is shown in the rightmost frame.  

So, what is a Data Focus object and how can you make one?  Let’s start by introducing the “Heatmap”, a new style for XY Plots, designed to manage heavy plot data when the content would otherwise overwhelm the Symbol/Line style.  Essentially, we use the plot axes to define the rows and columns of a spreadsheet.  Each cell defines a “box” whose upper and lower limits are based on a small range of both the vertical and horizontal axes.  We fill up the boxes, matching our input data to the bounding range for each cell.  Some boxes will be empty.  We can get a sense of how full each box is by using a scalar function to weight the results.   If we now color each cell in our spreadsheet based on the weighting, we see how our data is distributed within our XY plot.  The end result of this numerical manipulation is our “Heatmap” .  

The input for our XY plots can be any combination of derived parts, boundaries and/or regions – just drag them straight into the plot window.  For our flame simulation, we have the following two heatmaps, one showing temperature versus mixture fraction (weighted by temperature) and the other showing mass fraction O2 versus mixture fraction (weighted by mass fraction O2).

We begin by interactively creating a Data Focus object, or selection filter, dragging a rectangle onto our heatmap to focus on temperatures above 1500K.  Next, we create a compound filter by applying the first Data Focus filter to the mass fraction of O2 versus mixture fraction heatmap, and add a second selection filter focusing on the mid-range of the mixture fraction.  Since these XY plots are linked to the same Data Focus object, a change to either selection is applied to both.  Lastly, we apply this Data Focus filter to our scalar displayer showing the flame temperature at right. 

To see whether there is a part of the flame where the temperature is high and the mixture fraction is also low or high, you interactively drag the selection in either XY plot – the other XY plot and the scalar displayer get automatically updated.  And consider this.  For a single Data Focus object, you can create a compound set with multiple filters, no limit.  To that single Data Focus object, you can add any number of multiple compound sets, via interactive selection, no limit.  You can create any number of Data Focus objects, no limit.  You can then apply any one of these Data Focus objects to any displayer within a scene, or to an XY plot, no restrictions.  Simply put, there are no limits to the number, or complexity, of questions you can ask.  Talk about the student calling the teacher to task!  

I believe we run simulations because we want, and have the strong need, to learn.  We want to design better products and we want to be certain of what changes cause what effects.  To learn, we need to ask questions and Data Focus delivers an absolutely unprecedented and competitively unique way to do just that.  I’ll close here by paraphrasing Plato – “The unexamined .sim file is not worth running”. 

 

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