# Richard Smith's blog

## Turbulence Model Selection

Most Computational Fluid Dynamics (CFD) software provides an array of turbulence models. Knowing which model to select is not always an easy decision given trade offs between accuracy and computing requirements.

Turbulent Air Flow Behind a TruckGeometry courtesy of Nectar Design

## Double Diffusers and F-Ducts Explained

If you followed Formula 1 in 2009 and 2010 you will probably recall the terms double diffuser and F-duct. However, unless you were in the aerodynamics department of an F1 team during that period you will probably only have a sketchy idea of how these devices actually produced the elusive, race-winning, downforce that is key to F1 success.

Brawn GP 2009 BGP001: Double diffuser carLicense: CC BY 2.0, Jose Ma Izquierdo Galiot

## Fluid Dynamics News: Hydraulic Capsule Pipelines and Fish Farming Sea Cages

Time for some fluid dynamics news with a Computational Fluid Dynamics (CFD) slant. Check out how CFD was used to make hydraulic capsule pipeline predictions and simulate the flow through fish farming sea cages.

## Symmetry for CFD to the Rescue

Symmetry is a simple but powerful concept that you can use to speed up your Computational Fluid Dynamics (CFD) simulations and reduce your memory requirements. Join me in an exploration of a simple symmetry case.

CFD Simulation of a Symmetric Quarter ModelVelocity vectors

## Amazing 3D Maze Solved by CFD

If you were amazed at the 2D maze solving ability of Computational Fluid Dynamics (CFD) then you had better sit down and prepare to be even more amazed at CFD's 3D maze solving.

CFD 3D Maze SimulationVelocity vectors

## Amazing CFD

You already know that Computational Fluid Dynamics (CFD) is great at solving fluid dynamics problems, but did you also know it is able to literally solve mazes too? Prepare to be a-maze-d.

CFD Maze SimulationVelocity vectors

## In Search of The Remaining 20 in The Pareto 80-20 Rule

Pareto analysis usually reveals a golden 80-20 rule for squeezing performance out of things. In other words - it means the majority of the performance (80%) is typically governed by a minority (20%) of factors. Pareto analysis applies equally across many disciplines from sports (marginal gains anyone?) to product design.

Reducing Pressure Loss Through a BendCFD turning vane study

## Never Settle For Facets

Don't settle for Computational Fluid Dynamics (CFD) software that uses (abuses) facets (e.g., STL) as geometry. If your original geometry is analytic (CAD) then mesh it directly without the conversion to facets. Otherwise it's like you have to create two surface meshes. What's wrong with that? Plenty!

Blocky Structures Are Not The NormDartmouth clock tower undergoing renovation aided by blocky scaffolding

## When Good CFD Goes Bad

You've checked everything, and I mean everything, but still your Computational Fluid Dynamics (CFD) simulation does not resemble reality. Then it's time to consider the deeper underlying basis of your CFD software.

Mandelbrot Set From Chaos TheoryCFD Simulations are not immune from descending into chaos
License: CC BY-SA 3.0, Wolfgang Beyer

## How Aerodynamics Dominates The Tour de France

The spectacle that is the Tour de France (TdF) is all about aerodynamics - and you thought it was all about the bike. Virtually all tactics in the TdF are dictated by individuals or teams of riders attempting to limit their exposure to the 'wind', in order to minimize drag and therefore minimize the effort required to progress. There are some obvious and not so obvious tactics riders and teams employ to use aerodynamics to gain advantage.