What’s Driving Your Simulations?

To be a good simulation engineer, you need to ask “what if” questions. “What if we make this pipe longer?” “What if we change the thickness?” “What if we change the material?” However, if you have a complicated assembly or part, it’s easy to say, “I don’t want to model it again. That took forever.” Well, the solution has arrived: You need to become a better modeler.

Recently, I was introduced to parametric modeling by my partner in crime, Nick B (or #2, as I call him). It took a while before I realized its potential in regards to optimization and these so called “What if” scenarios.

Once a multi-body part or assembly is parametrically driven, changing values become much easier to do.

To illustrate my point, I’ll breeze through the modeling process for the design of a solar thermal unit. With a setup like this, a good engineer will ask questions like, “What if we add pipe passes?” and “What if we make the passes closer together?” If the model isn’t setup correctly, these changes are difficult to make. So, we’ll design with the intention of changing it later.

Let’s get started with the first pass of the copper tube. A sweep is done and the model is dimensioned and linked accordingly.

The next thing to do is create a linear pattern, linking the spacing value with the pass width and iteration values.

We then create “plane 1,” normal to the right plane and define its spacing with an equation, relating the number of pass iterations with the pass distance.

Plane Distance = (# of passes)*(pass distance)

At this point, the reason for the plane might seem unclear. However, the protective box and heat sink will reference this plane.

We then create merged pipe extensions using linked values while referencing the default right plane and plane 1.

When sunlight travels through the glass opening of our solar panel, only a small percentage of sunlight will actually hit the pipe. So, we need to create a heat sink which will capture radiation from the sunlight and transfer heat via conduction to the copper tubing. We’ll do this by creating a single sheet metal piece with linked values, then pattern it with linked values and equations.

Heat sink iterations = (# of passes)*2 +1

The next step is to create the protective box and glass cover. The geometry is defined using existing relations, similar to what we’ve already done.

Now, if I change values, like the number of tube pass iterations or tube space distance, the entire model updates automatically. This will come in handy when running optimization simulations and playing with other what if scenarios.