For aerospace engineers, wind tunnels are commonly used to test aircraft and engine aerodynamics. This type of evaluation began at the end of the 19th century, in the primitive days of aeronautic investigation. To date, there is no wind tunnel that can test the full size of a passenger air vessel, but tunnels do range in size and can test everything from large-scale models of airplanes and other aerospace vehicles to small-scale prototypes and replicas.
When testing aircraft, the lift and drag forces are measured through outputs received from force balance testing and resulting balance signals. Pressure forces are quite difficult to evaluate in a full-scale aircraft simulation due to the number of instrumental pressure taps required. Through wind tunnel experiments, a diagnostic test can not provide overall aircraft performance, but can help the engineer to better understand how the fluid moves around and through the model. This is because different types of instrumentation can be employed, from steady state or unsteady flow to time-varying or time-dependent, but not in parallel for a holistic understanding.
For many aerospace applications, wind tunnel experiments are limited by not providing robust results in a timely manner or failing to simulate real-world forces accurately enough. Virtual simulation, or online CFD and FEA, can make this possible. For example, the behavior of aircraft landing gear in reaction to stresses as a result of the airflow against the motion of the airplane can be studied. This project along with the post-processing image below provides a great example of how the results of virtual wind simulation can help engineers compare different designs as well as various materials to be used for the multiple components that go into the simple-looking but complicated structure.
As aerodynamics plays a significant role in the performance of automobiles, good aerodynamic planning helps augment the down-force and hence, the traction of the vehicle on the road, mitigating risk of lift-off, skidding, and potential accidents. Along with this, reducing drag force decreases fuel consumption, which in turn saves money for the consumer and reduces the carbon footprint of the product. When designing a car, engineers are increasingly relying on CFD simulation before the initial model is created in order to evaluate the predicted airflow around the vehicle, computing the regions of high pressure, wind velocity, and wake regions. This project, and image below, provides a great example of how employing a virtual wind tunnel online via steady state turbulent flow analysis with the K-Omega SST turbulence model can give valuable insights and save time and money compared to stand alone wind tunnel testing.
With the influx of development in the construction industry, and the social demand for increased residential, commercial, and industrial buildings, the built environment is expanding like never before. With this comes an urban density increase paired with a skyline extension horizontally and vertically; sometimes the only space to build is up! With new, taller structures becoming the norm, the structural safety of these buildings must be evaluated. Structural integrity is often determined by its structural design to withstand wind loads, whereas the habitability of the buildings for living or working is often hindered with wind-induced vibration. In order to properly evaluate both structural integrity of wind-loading and habitability from the effect of across-wind vibration, wind tunnel testing of small-scale models is a method predominately used.
In order for architects and civil engineers to approve a design, Standard ASCE/SEI 49-12 provides minimum requirements for evaluating wind tunnel experiments in order to determine acceptable wind loading on built structures. This guideline takes into consideration wind loads, structural response to wind conditions, as well as cladding for a variety of wind-related weather conditions. Additionally, due to the crowding of structures in urban locations and the trend of atypical design of structures, the effect of wind is becoming harder to anticipate as it is constantly changing, and as a result, the pedestrian level wind environment is becoming more and more affected.
To comply with all ASCE guidelines, FEA to determine structural integrity along with CFD to evaluate other aspects of wind loading and vortex shedding must be applied. This project and accompanying image provide a perfect example of both investigations being made possible through online simulation, as another way to verify and validate designs before constructing.
In addition to the effects of wind on buildings, the pedestrian-level wind environment must also be taken into consideration. While wind tunnel testing fails to focus on this level of intricate analysis, CFD can be employed to pinpoint areas of harsh winds, recirculation, and general pedestrian-level discomfort, as shown in this project from SimScale.
With CFD and FEA from platforms like SimScale, engineers can easily access, evaluate, and get results from a virtual wind tunnel online. Using cloud-based simulation, you can even run simulations in parallel to test multiple design iterations at the same time, or investigate different aspects of a design in tangent, like vortex shedding and wind loading as shown in the aforementioned project. Virtually evaluating designs not only saves operational costs and time, but saves resources by eliminating the need for physical prototyping.
There have already been a number of professional and elite athletes who have begun working with STAC Performance, including Cody Beals, who is known for being meticulous when it comes to his product selection. STAC claimed that they were able to replicate Cody's previous wind tunnel results to within 2% of his measurements using their VWT. I had the chance to discuss STAC Performance with Cody who was initially drawn to STAC more as a would-be investor than a potential sponsorship.
Why did you decide to partner with STAC Performance?
"STAC caught my attention early on due to its groundbreaking technology and proximity to my home in southern Ontario. My background in physics, fascination with aerodynamics and fondness for indoor cycling made both the Virtual Wind Tunnel and STAC Zero trainer very intriguing. On top of innovative tech, I was impressed by the enthusiasm, vision and obvious brilliance of the people behind STAC. The STAC Zero trainer and the VWT are just the tip of the iceberg for this young company. I recently visited the STAC headquarters and couldn't believe all the concepts, prototypes and wild ideas casually strewn about the shop or floated in conversation."
I have done some very basic exploratory research using Autodesk CFD software. It's fully functional for a trial period of 30 days, but can be used multiple times (instructions upon request in PM). The 3D model was created in Catia, but the CFD software accepts many different formats.
I would like to ask for help from any people that are knowledgeable in this area, people that are good in 3D modeling and basically anyone else willing to contribute, to help me out in setting up proper wind tunnel analysis and results post processing. I do have a Master's in Engineering, but I got my degree some time ago and I am quite rusty in fluid dynamics, meaning I suck at it.
Here are some pictures from the initial trials.
Did you know that SOLIDWORKS Flow Simulation is built upon technology originally used for aerodynamics? Whether you're designing products to be mounted on aircraft or a whole new airframe itself, SOLIDWORKS Flow Simulation provides a quick way to test for familiar parameters like Lift, Drag and even Reynolds Number, all with the ability to quickly visualize and compare the behavior of design changes. Join Product Manager, Damon Tordini, as he reproduces a real-world wind tunnel test in a fraction of the time.
I wanted to share this interesting artistic simulation of fluids in blender 3.5. I basically created a wind tunnel with an airfoil, and I inserted 1 million particles with RK4 solver (I used particles because they take into account the compressibility of the air, so the final effect is more realistic). Then I hooked a smoke simulation of 256 subdivisions to each single particle. Surprisingly the baking took only 10-12 minutes on an AMD Ryzen7 3700X, and the (non-final) rendering only 6.98 seconds on an NVidia RTX3060 12Gb, setting the appropriate parameters. If you like it I will post more images with more complex renders. I used this semi-realistic approach to finally learn how to artistically handle the beautiful world of fluid simulations in Blender, which is certainly very useful in computer graphics.
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