# Richard Smith's blog

## CFD Prefers NURBS Over STL

Let me explain why, given the option, you should prefer analytic geometry (e.g., NURBS) over faceted geometry (e.g., STL) for Computational Fluid Dynamics (CFD).

CFD Mesh for a Faceted WheelNote spurious flat spots

## DIY CFD

If fluid flow is a primary driver for your design project then Computational Fluid Dynamics (CFD) is likely to be a cost effective way to help meet your goals. You could outsource your CFD to consultants, but in the long run it usually pays to do it yourself.

Dust Collector CFD Simulation

## How to Control Your CFD Simulations in Caedium

The Caedium Simulation Control Toolbar provides the controls to initialize and run your Computational Fluid Dynamics (CFD) simulations. Take a moment to learn how to use these simulation controls effectively.

Caedium CFD SimulationAfter a single step of iterations

## How to Control Your CFD Mesh in Caedium

The Caedium Accuracy tool is largely responsible for determining the accuracy of your Computational Fluid Dynamics (CFD) simulations by imposing constraints on the underlying computational mesh or grid. Therefore, it's worth spending a moment to learn how the Accuracy tool in Caedium works.

Volume Mesh Elements

## Walkalong Tumblewing Meets CFD

To complete this series of Computational Fluid Dynamics (CFD) on simple rotating paper wings, we now turn our attention to the walkalong tumblewing.

CFD Simulation of a Walkalong TumblewingVelocity vectors at 0 degrees

## Tumblewing Meets CFD

Although a sheet of paper can be made to fly by spinning, it isn't always reliable. By adding winglets and flaps with 4 simple folds we can improve the stability of the wing and in so doing produce a tumblewing. How do the aerodynamics of a tumblewing compare with a sheet of paper? It just so happens Computational Fluid Dynamics (CFD) can help, just as it did with the simulation of the spinning sheet of paper.

CFD Simulation of a Rotating TumblewingPressure iso-surfaces at 90 degrees

## Spinning Paper Sheet Meets CFD

I don’t think anyone would argue with the fact that paper airplanes are simple (and fun!), but what is the simplest paper airplane that can still fly? I give you a single rectangular piece of paper without any folds that will gently spin around its longest horizontal axis if released with a long edge parallel to the ground. Next, what is the simplest Computational Fluid Dynamics (CFD) method that can capture the essence of the spinning paper? I give you the Moving Reference Frame (MRF, also known as the frozen rotor method) option for CFD. Combine the two and you arrive at an interesting simulation of a simple phenomenon.

CFD Simulation of a Rotating Paper SheetVelocity vectors at 90 degrees

## Get Started With CFD

New to Computational Fluid Dynamics (CFD)? Then you've come to the right place. Becoming productive in CFD can be a daunting task. However, as with all long term goals, if you break it down into smaller, achievable tasks, in no time you'll be up to speed and ready for production level work. Assuming you are familiar with the fluid dynamics of your application, then let's begin.

CFD Simulation in Caedium

## Caedium Clarified

Based on the inquiries we receive concerning Caedium and our business model I thought it would be useful to share the most common clarifications. Also you can find answers to common questions in our FAQs. Don't see the clarification that you seek? Then feel free to ask your question in the comments below.

Caedium Professional in Action

## Here Come The Drones

It used to be that to design and build a flying machine was an expensive endeavor, what with pilots, wind tunnel tests, prototypes, etc. Not any more though - welcome to the brave new world of Unmanned Autonomous Systems (UAS) or Unmanned Autonomous Vehicles (UAV) or, more popularly, simply drones. How did we get to this point and where is it going? What role, if any, will Computational Fluid Dynamics (CFD) play in this drone future?

Quadcopter DroneBy Airbunny (Own work) [CC BY-SA 3.0], via Wikimedia Commons