CFD Study of a Barbeque Smoker

By Joe McDonough on

In today’s blog we are going to be showing our CFD tool Flow Simulation. CFD applications can yield some amazingly powerful results that can help make important design decisions. In today’s blog, we are going to use a basic CFD study of a barbecue smoker to show the tips and tricks of setting up and post processing your results!

Tricks for Setting Up a Study

When setting up a flow simulation study, there’s a few things that almost every study needs to do. Applying boundary conditions to your study is how we describe the real-world application. When doing things like selecting where to apply the conditions we often need to pick groups of faces or even the inside of a lid enclosing our fluid volume. The Select Other tools can be amazing time savers. The select other tool allows users to select the inside face of a lid that is bordering the fluid boundary.

select other tool

Cut Plots

Depending on the application and geometry the best type of post-processing plot changes with your needs. However, one plot is consistently used to understand the fundamentals of study time and time again, the cut plot. Cut plots are a fantastic tool for analyzing your studies, but they have many hidden features and tools that not many users take advantage of.

Below are two very different cut plots of the same parameter but are showing very different levels of info. On the left can be very useful for understanding the basic boundary layers in our smoker. But on the right, we have a much more detailed cut plot showing a much smoother color gradient as well as dynamic velocity vectors.

There are two types of vectors we can use static and dynamic velocity vectors. Static is stationery as we zoom in and is good for creating one consistent graphic, while dynamic vectors allow us to overlay the velocity over any other type of result giving us a better understanding of why an area may have cool or hot spots. Along with this dynamic velocity, vectors change density of arrows as we zoom in and paint an even clearer picture of our flow. With these vectors, we recommend trying out differing sizing and spacing to see what fits your application the best – visually speaking.

adjusting sizing

Cut plots are a slice of the fluid computational domain, this makes it extremely easy to understand on that plane. We can play a cut plot by simply right-clicking and hitting play which will move our cut plot in the normal direction throughout our fluid volume. When doing this, we often see varying gradients throughout the volume showing that even when looking at one slice of the volume, the legend is scaled for the entire computational domain. If we have a specific area we are analyzing, the legend may have a legend that is not scaled to our plot’s maximum and minimum. To correct this, follow the steps below.

  1. Edit the cut plot definition.
  2. Select your plots you want to show (contours, vectors, streamlines etc.).
  3. Select your results from the drop-down menu.
  4. Next to the drop down hit the scale.
  5. Two options we can use to scale the max and min are manual or automatically scale by the solver.

Flow Simulation is an extremely powerful program with many small ways to fine tune how your team creates studies and post-processes your results. Look out for our webinars and blog content to learn more or if you need to strengthen your skills from the ground up reach out to your TriMech contact about training opportunities!