Virtual wind tunnel: aerodynamics and drag simulation

What is a virtual wind tunnel?

A wind tunnel blows air past a model so you can see and measure what the air does. A virtual wind tunnel does the same on a computer: you place a shape in a simulated stream of air and solve for the flow around it. This is airflow simulation, or aerodynamics simulation, and it is computational fluid dynamics (CFD): the same idea used in professional aerodynamics work, applied here to learning and exploring.

As flow simulation software, Visaria gives you a full 3D simulation with GPU acceleration and turbulence modelling, so you can see where the air speeds up, where pressure builds, where the flow separates and where it swirls behind the shape, and watch it respond as you change things.

What you can see and control

• Streamlines, flow speed and pressure around and behind your shape.
• Recirculation and turbulence: where the flow separates and tumbles.
• Boundary conditions you can inspect and change, including a moving road, symmetry and the size of the flow domain.
• Default and custom mesh sizes, and a nested fine grid around the part you care about.
• Convergence plots and solver information alongside the simulation, so you can see when the flow has settled.
• Force coefficients such as drag and lift, shown as a guide to how the solution is converging.

Bring your own shape

Load an STL file from your CAD program, or build a shape in the Mesh Builder from primitives and boolean operations. STL is a standard export from most CAD tools, such as Fusion 360, and from 3D printing software, so you can bring in the model you have already made: a car or truck body, a model rocket, an RC car, a cycling helmet or bicycle part, a drone arm or a wing section. Car aerodynamics simulation is a good first project, because the effect of the shape on the wake and the drag is easy to see. Visaria voxelises the geometry automatically and you press run.

Then ask the questions that matter to you. Does a rounder nose help? What happens to the flow behind a blunt tail? How much does a spoiler change the wake? You can change the geometry or the wind and compare, one variation after another, in minutes.

Understanding drag

Drag is the force that resists motion through air. It comes from pressure differences around the body and from friction in the thin layer of air next to its surface. Streamlining reduces it by keeping the flow attached for longer and shrinking the turbulent wake. Reading this is one thing; watching the wake shrink as you smooth the shape is another, and that is the learning Visaria aims for. The Learning Hub has short primers on these ideas with links to scenarios you can adjust.

How accurate is it?

Visaria uses a coarse voxel grid and solvers tuned for real-time use. It is built for understanding and quick comparison of ideas, not for engineering-grade numbers. Its drag and lift values are indicative, a convergence monitor rather than a validated measurement, so do not use it for certification or for design decisions where accuracy matters. Use it to see why, then use a validated tool or a real wind tunnel for how much.

The Aero solver is included in the free 7-day trial and in the Pro Bundle, and can be bought on its own. See pricing.

What you need to run it

Visaria runs on Windows and needs a dedicated graphics card: an NVIDIA GeForce GTX 1050 or AMD Radeon RX 560 is the minimum, and an RTX 2060 or RX 5600 XT or better is recommended, with an 8th-generation Intel Core i5 (or equivalent) and 8 GB of memory. Mac and Linux versions are coming soon. The free trial is the quickest way to check that it runs well on your computer.