Follow Along: Flow Analysis

Now that we’ve added our simulation model and our boundary conditions to our Flow Analysis block, let’s add a cell size and run our analysis. This cell size input defines the Cartesian mesh on which this analysis will run. We’ll add a cell size of 0.75 mm.

Before the flow analysis runs, it’ll calculate the available GPU memory. Available GPU memory will be based on how much nTop and other programs are using. Of course, a smaller cell size will also increase the number of cells, causing you to need more GPU memory. To help maximize your available memory, I would suggest changing your resolution to low. If you still have insufficient memory to run your flow analysis, you’ll see an error appear on your block properties. To view the progress of your flow analysis, you can open your log panel in the bottom right corner and expand it to see your progress.

Now let’s view the results of our flow analysis. You’ll see this color map across your domain representing both your instantaneous and time averaged pressures and velocities. The instantaneous values represent your instantaneous results from your last time step. Your time average results smooth the fluctuations throughout your simulation to reveal your mean flow structure. In your display panel, you can switch from the domain mode to the streamlines mode. Here you can see the streamlines of the fluid moving through your domain. You can adjust your seed count or you can specify an individual seed. Doing this will allow you to take a sphere and drop it at any point within your domain. Here you can adjust your radius and visualize the upstream and downstream behavior of the fluid moving through that region.

Now we’ve finished running our flow analysis, so I’ll right-click and make it a variable to mark these results. Navigating one more time to the fluids tab, I’ll expand my utilities drop-down and add a block called Flow Analysis Results On Boundary. This will allow us to evaluate average flow analysis properties on specific boundaries. For example, if I wanted to find my average velocity at my outlet, I could simply drop my flow analysis results into this block. Specify my property field by opening the properties of my flow analysis and expanding my velocity drop-down to compare my keys and expand those list elements to find index number two or my time average velocity with my values, grabbing that second length in my list elements, and then applying my boundary at my outlet. This Flow Analysis Results On Boundary block will specify my time average velocity at my outlet, which is 8.7 mm/s.

I’ll right-click, make this a variable, and call it outlet velocity. I can repeat this process for any result field on any boundary.

0:00 Adding Cell Size and Running Analysis
0:24 GPU Memory and Error Handling
1:17 Viewing Flow Analysis Results
2:41 Using Flow Analysis Results On Boundary