Pitot tubes are critical devices used to determine the airspeed of an aircraft. In aerodynamics it is important to know the speed of an aircraft relative to the surrounding air to alert pilots to stall conditions. Pitot tubes are also used in wind tunnels to determine airspeed, sometimes using a manometer to measure the pressure difference between static pressure and total pressure to determine the dynamic pressure. I thought it would be interesting to see if we could simulate a pitot tube connected to a manometer (two-phase flow, air + water) using Computational Fluid Dynamics (CFD) and to share my findings with you.

CFD Simulation of a Pitot Tube and ManometerBlue is water and red is air

Welcome to the concluding episode of my two-part project to compare results between the virtual wind tunnel and free air using a series of Computational Fluid Dynamics (CFD) simulations. Recall that the previous post outlined the free air tests and expectations for the comparison. Here I present the results and conclusions.

CFD Simulation of a Racecar in a Wind TunnelPressure contours on the racecar

Often the ultimate aim of performing a wind tunnel test on a scale model is to provide data on how the full size equivalent will behave in free air. This is especially true in motor racing (e.g., Formula 1) where teams use a combination of wind tunnels and Computational Fluid Dynamics (CFD) to guide what they hope is a winning racecar design. As a follow on to my project to build a virtual wind tunnel to test an open wheel racecar, here I start a two-part project to compare results between the virtual wind tunnel and free air using a series of CFD simulations.

CFD Test Section for a Racecar in a Wind Tunnel

Having recently built a Computational Fluid Dynamics (CFD) simulation of the Honda Wind Tunnel at Imperial College, it seemed only fitting to actually use it to perform a virtual test on a scale model. Clearly, given the wind tunnel's close association with motor racing, the test model had to be a racecar.

CFD Simulation of a Racecar in a Wind TunnelVelocity magnitude iso-surfaces

Have you ever wondered what are the main features of a wind tunnel and what purpose do they fulfill? Well wonder no more. With the help of Computational Fluid Dynamics (CFD) let's explore a closed return wind tunnel based on the Honda Wind Tunnel at Imperial College, London.

Wind Tunnel CFD SimulationVelocity magnitude iso-surfaces

A Moving Reference Frame (MRF) is a relatively simple, robust, and efficient steady-state, Computational Fluid Dynamics (CFD) modeling technique to simulate rotating machinery. For example, the rotors on a quadcopter can be modeled with MRFs.

MRF CFD Simulation of a Quadcopter in FlightShows streamlines colored by velocity magnitude

3D printers are the new black.

• "3D Printing will be bigger than the web", Chris Anderson, ex-Wired editor
• "Why MakerBot is Like Apple", John Biggs, TechCrunch
• In US$403M deal Stratasys buys MakerBot

Whether 3D printing can live up to the hype remains to be seen. However, making things has been around since time eternal. The fact that 3D printers have reached a price point allowing small businesses and hobbyists, collectively referred to as Makers, to leap on board is definitely exciting. However, what hasn't changed is that building a physical thing still costs time and money. What can we learn from the millennia of building things prior to the availability of 3D printers?

First Generation 3D Printer for HobbyistsCourtesy of Fab@Home

Helical strakes are often used on chimneys to reduce vortex induced vibration (VIV). However, these strakes also have a significant drawback - they induce massive increases in drag and side forces that have significant structural implications for the chimney. Read on for a Computational Fluid Dynamics (CFD) study that compares a smooth cylindrical chimney to the same chimney with helical strakes.

CFD Simulation of a Helical Strakes ChimneyVelocity magnitude contours

Do you want turning vanes with your duct work? Yes, if you are considering a square corner and you want to minimize your fan power requirement. Don't take my word for it, instead consider this Computational Fluid Dynamics (CFD) study that compares a vaneless square corner with both small turning vanes and large turning vanes.

Turning Vane CFD StudyVelocity magnitude contours on the symmetry plane

Zoology professor Warren Porter leads a team of researchers from the University of Wisconsin-Madison that uses Computational Fluid Dynamics (CFD) to simulate heat transfer and drag. No big deal you say, until you hear that the subject of his CFD simulations is an elephant!

Caedium CFD Simulation Around an Elephant