Every 4 years the FIFA World Cup rolls around and the question on everyone's lips is...how will the official match balls behave? Oh, and to a lesser degree, which nation will win?  Ball aerodynamics are complex, but relatively well understood. Given the typical speed and spin of balls in the beautiful game, small changes to their surface texture (the focus of much recent effort in ball design) can have dramatic repercussions on their trajectories and hang times. Balls are deemed so important that each has its own Wikipedia page and each has tournament-flavored names thanks to Adidas, the long time ball designer.

CFD Simulation of Flow Around a Rotating Ball

Complete, watertight, complex geometry is a rare but welcome find in Computational Fluid Dynamics (CFD). However, thanks to the steering committee of the upcoming 23rd International Meshing Roundtable, such a geometry, in various formats, is freely available for their meshing contest. The star of the contest is London's Tower Bridge, I presume in honor of the conference's host city. So to the bat cave to see what Caedium Professional can do with this model.

Tower Bridge Caedium CFD SimulationVelocity contours

It is a common occurrence: a rain drop falls into a puddle; a leaky faucet drips into a sink of water. This seemingly simple event has some complex physics in play that advanced multi-phase, free-surface (volume of fluid - VOF) Computational Fluid Dynamics (CFD) can simulate. Not only can CFD simulate water impact in a pool, it can also produce a beautiful 3D visualization of the process as an animation. Follow along to see how you can use Caedium Professional to simulate a water droplet falling into a pool of water.

VOF Free Surface Caedium CFD SimulationDroplet crater

The next release of the Caedium CFD software system will be able to simulate the convection and diffusion of a passive species, also known as a passive scalar. A passive species can represent and track additions such as smoke in airflow and dye in water. It can also provide insights on the dispersion of pollutants carried by a fluid.

Caedium Passive Species CFD SimulationPollutant plume released in air from a chimney

Previously I showed how to automate a sequence of Caedium Computational Fluid Dynamics (CFD) simulations of an alpha sweep for an airliner. Next up I will show you how to automate the export of results from Caedium in a specific format. This example focuses on the files required for ixCube 4-10 (the successor to ixForten 4000) to perform a structural analysis using the pressure coefficient (Cp) from an airflow simulation over a tensile structure or membrane.

Caedium Membrane CFD Simulation

While I'm sure you know aerodynamics does play a crucial role in outdoor cycling, aerodynamics doesn't offer any performance gains for stationary cycling indoors. With this in mind, hopefully you spotted that my previous blog post "Aerodynamic Performance of a Stationary Bicycle" was a cunning April Fools' Day ruse.

Stationary Bicycle StreamlinesNo airflow, no streamlines

Aerodynamics plays a crucial role in the performance characteristics of outdoor cycling. However, no-one to my knowledge has used Computational Fluid Dynamics (CFD) to analyze the aerodynamic performance of a stationary bicycle - at least until now!

SketchUp Model of a Stationary Bicycle and Cyclist

Computation Fluid Dynamics (CFD) is synonymous with impressive 3D visualization. Learn more about the basic 3D visualization techniques in CFD and how they can help you reduce the mass of raw data from a simulation into insightful and beautiful graphics.

3D Visualization in CaediumCFD simulation of a cyclone

Turbulence modeling for the Reynolds Averaged Navier-Stokes (RANS) equations - the basis of most industrial Computational Fluid Dynamics (CFD) software - is a complex field. Trying to strike a balance between accuracy and computational efficiency has given rise to a relatively large number of different turbulence models. I am not aware of a definitive list to match turbulence models to applications - if you are, please share! With this in mind I'll share 6 suggestions before you consider switching the default turbulence model in your CFD software.

RANS CFD Simulation of Air Flow Around a ChimneyUsing the k-omega SST turbulence model

You've already heard some of the advantages of using co-processing over after-the-fact post-processing, but there's more. Co-processing is an enabler of Computational Fluid Dynamics (CFD) simulation 'steering', i.e., making changes to the simulation while it is active.

CFD Simulation Steering in CaediumRelaxation factors changed at 200 iterations