RYURAKU - Fluid Dynamics

RYURAKU is an interactive educational simulation app for experiencing fluid dynamics phenomena firsthand. Developer: Fuji Bit Inc. The 6th title in the SUUGAKU / BUTURAKU / DENRAKU / HARAKU / NETURAKU series. The theme is "flow." Discover the wonders of fluid physics through 12 hands-on simulations. 12 simulations in 3 categories: - Flow basics - Streamlines: particles reveal potential flow around a cylinder in a uniform stream. Drag the obstacle and watch the flow field change in real time. - Bernoulli's Principle: flow through a Venturi tube with live pressure gauges. Watch speed rise and pressure drop where the pipe narrows, and see A1v1 = A2v2 at work. - Reynolds Number: laminar-turbulent transition in pipe flow. Adjust speed, viscosity and diameter and see the dramatic change at Re ≈ 2300. - Boundary Layer: a boundary layer growing over a flat plate, from the laminar Blasius solution to turbulent transition at Re_x ≈ 5×10^5. - Darcy's Law: slow flow through porous media such as sand or rock. Adjust permeability, pressure gradient and porosity to experience q = (k/μ)·∇P, the law behind groundwater, oil reservoirs and filters. - Vortices & lift - Vortex: point vortices and their mutual induction. Tap to add a counterclockwise vortex, long-press for clockwise. - Kármán Vortex Street: alternating vortex shedding behind a cylinder, with live Strouhal and Reynolds numbers. - Lift Force: flow around an airfoil and how lift and drag arise. Change the angle of attack or camber and watch the force vectors. - Magnus Effect: asymmetric flow and a sideways force on a spinning cylinder: the physics of curveballs and banana kicks. - Water & gravity - Buoyancy (new): Archimedes' principle. Change the object and fluid densities to find where things float, sink or hang in balance. Drag the object under, let go, and watch it bob until it settles with a submerged fraction of ρ_s/ρ_f. - Torricelli's Law (new): water jetting from a hole in a tank. See the exit speed v = √(2gh), the falling water level and the jet range R = 2√(y₀h). Drag the hole to find the height that throws the water farthest. - Surface Wave: free-surface gravity waves. As the depth-to-wavelength ratio changes, particle orbits shift smoothly from circles (deep water) to flattened ellipses (shallow water). Features: - Real-time parameter adjustment for every simulation - A hint on how to try each screen, plus an explanation with formulas - Live physics formulas and values - Works with large text sizes, landscape, iPad and Split View - Taps and drags can also be done with buttons and sliders (works with VoiceOver and Switch Control) - 16 languages (English, Japanese, Chinese Simplified / Traditional, Korean, Spanish, Portuguese, German, French, Hindi, Indonesian, Russian, Italian, Turkish, Thai, Vietnamese) - Dark mode / Light mode Pricing & ads: - Free. No in-app purchases, subscriptions or paid unlocks - A banner ad (Pangle) is shown at the bottom of the screen - Ads are personalized only if you allow tracking (ATT). You can also turn off personalized ads from "About this app" > "Ad settings" Recommended for: - Students studying fluid dynamics in physics class - Anyone who wants to understand how flow behaves - Teachers looking for interactive teaching materials - Anyone interested in aeronautics or fluid mechanics