r/aerodynamics

I dont have access to StarCCM anymore and I'm out of Fusion Sim credits at work.

I’m developing a DIY aerodynamic upgrade kit called Slipstream, built around a LiDAR scan → CAD model → modular panel workflow. The goal is to reduce drag on existing vehicles without requiring permanent body modification.

The current module set includes:

• Smooth wheel covers
• Rear wheel skirts
• Underbody panels
• A short, removable boattail
• Clip‑on mounting system designed to avoid drilling or adhesives

Everything is meant to be reversible and installable with basic tools.

I’m not looking for hype — I’m looking for the first aerodynamic flaw that stands out to you. Whether it’s panel transitions, taper angle, stagnation zones, separation risk, or something I’m overlooking entirely, I want the honest critique.

If you were evaluating this as a real aero package, what’s the first thing you’d fix or question?

I’m building this in the open, so detailed feedback is extremely helpful.

ARGUE WITH ME

If a smaller cylinder and a larger one are both exposed to an air current at the same speed, do they have the same separation point?

How would the study of aerodynamics change if humans were the size of giants or that of ants? Would a cylinder the size of a giant and one the size of an ant have the same separation point?

The question arises from the fact that a cylinder is large or small relative to my size: a cylinder that is large for an ant is a small cylinder for me.

I’m writing a character that uses an extremely long lightweight cloth (like nylon or chiffon) that stays elevated through urban airflow. The cloth is very thin with cuts like a snake spine to reduce spinning and catch airflow better, the cloth also is segmented into 3 parts

I have a few questions:

Realistically, how high could something like this get using urban wind, thermal updrafts, or train piston effects?
\- What design details could make it more believable? (vents, tapered shape, metal threading, etc.)
\- What environments would realistically keep it airborne the tallest? Subway grates, rooftop wind tunnels, industrial vents, heated streets between buildings?

This is my first time using reddit and I’m unsure which subreddit is appropriate for this question so please go easy on me.

Vertical Propulsion Design Helpp

Folks, I need help with a design. I am a novice at this so any help works. I want a Propulsion design that could lift (motor's weight + circuit) to a metre height. I need suggestions for most optimum Propulsion designs since I don't know jacksh- about aerodynamic systems. So please help me.

Has anyone here seen a genuinely high-resolution study of the earliest-time acceleration regime for objects moving vertically through fluids before substantial drag closure develops?

I’m interested in controlled comparisons using:

* identical density ratios,

* identical masses,

* but different geometries (sphere vs cylinder vs hemispherical-ended capsule),

* and ideally different surrounding media adjusted to equivalent densities.

The reason I ask is that most literature and demonstrations focus heavily on terminal behaviour, while the initial acceleration window seems comparatively underexplored experimentally despite being potentially important for separating:

* density contrast effects,

* added-mass coupling,

* geometry-dependent participation,

* and later drag evolution.

Would appreciate pointers to papers, datasets, or experimental groups working on this type of problem please.

Thankyou.

Hi everyone!

Some of you are working in motorsport so I'm sure this will help you at least a little bit.

Over the last few months I built a web app for motorsport wing design which lets you download and simulate your projects. It has:

• Built-in airfoil library (but you can also import a custom airfoil shape)
• Parametric setup (chord, span, AoA, endplates)
• Multi-element wing designer (up to 3 elements) - gap/overlap setup
• Modifiers (Curvature & Variable AoA - different AoA on the wing tips vs its core)
• Export 3D files in .STEP & .STL format (for free)
• Possibility to save your projects and airfoil profiles for further work

There's also a simulation tool based on XFOIL - that outputs crucial information on your design (CL, CD, L/D, stall margin). Additionally, it gives a proper PDF report with more in-depth analysis (Cp distribution, Pressure vectors, Transition location, Boundary-layer health & Separation bubbles). It's not for free since it consumes a bit of CPU but everyone gets free tokens to try it out. All the other features remain FREE.

It started as something I made for my own use. Figured it might save someone else a few hours too. Feedback welcome - especially from anyone actively doing aero work.

You can try it out here: https://www.aerodesignstudio.com/

If you have trouble using these features, you can watch this video which covers what's new and how to use it - https://www.youtube.com/watch?v=ZxLITPJSy78

https://preview.redd.it/jjhyr0obi30h1.png?width=3840&format=png&auto=webp&s=a592b97c6f5d8bfadc0b9d9d579f854ff69baa9a

https://preview.redd.it/28lxhu2ai30h1.png?width=3840&format=png&auto=webp&s=05ead9908bb062b1a3d4e02cf8d6a09678c64008

I’m curious if there are any alternatives to using CFD for getting lift, drag, and moment values for airfoils (and 3D wings) at angles of attack greater than about 20 degrees.

Are there versions of source/vortex methods that can approximate stall/flow separation? Flow separation is incredibly unsteady, so I’m thinking something like time averaged forces. Maybe something built from empirical data?

The application of this at least in my case is to get force and moment data of an aircraft (something simple, just lifting surfaces and a slender body fuselage) that can be used as lookup table data for flight simulation.

That brings me to a followup question, how do flight simulations such as Microsoft flight sim or Xplane figure out stall or high crosswind characteristics? I imagine some aircraft can use real data from someone purposely stalling an aircraft like a small Cessna, but certainly not for large aircraft like jets, right?