流楽

RYURAKU is an educational simulation app that allows you to interactively experience the physical phenomena of fluid dynamics.

This is the sixth installment in the series, following SUUGAKU (Mathematics), BUTURAKU (Physics), DENRAKU (Electricity), HARAKU (Waves), and NETURAKU (Heat). The theme is "flow." Through 10 simulations, you can learn about the mysteries of fluids and the profoundness of physical laws while having fun.

【10 Simulations】

1. Streamline Visualization: Visualize potential flow around a cylindrical obstacle using particles. You can move the obstacle by dragging it.

2. Bernoulli's Theorem: Experience in real time how flow velocity increases and pressure decreases as the tube narrows in a Venturi tube.

3. Vortices: Vortic generation and mutual induction using a point vortex model. You can add counterclockwise vortices by tapping, and clockwise vortices by long-pressing.

4. Reynolds Number: Visualize the transition between laminar and turbulent flow in a tube. You can experience the dramatic change in flow at the critical point where Re ≈ 2300.

5. Lift
Visualize the flow around an airfoil and the mechanisms of lift and drag generation. You can learn the principles of flight by changing the angle of attack and camber.

6. Karman Vortex Street
Visualize the phenomenon of alternating vortices being released behind a cylinder. The Strohull number and Reynolds number are displayed in real time.

7. Boundary Layer
Visualize the development of the boundary layer on a flat plate. You can experience the transition from laminar to turbulent flow based on the Blasius solution.

8. Magnus Effect
Visualize the asymmetry of flow around a rotating cylinder and the generation of lift. You can learn the principles of curveballs and banana shots.

9. Darcy's Law [NEW]
Visualize seepage flow in porous media. You can experience the fundamental law q = (k/μ)・∇P that governs groundwater, oil reservoirs, and filters.

10. Surface Waves [NEW]
Visualize gravity waves on a free surface. Based on Airy theory, the dispersion relation ω^2 = gk・tanh(kh) allows you to experience the continuous changes between shallow and deep water waves.

[Features]
- Parameters can be adjusted in real time for all simulations
- Physical formulas and values ​​are displayed in real time
- Japanese / English support
- Dark mode / Light mode support
- Works offline (internet connection only required for ad delivery)

[About Billing and Ads]
- This app is free
- There are no in-app purchases, subscriptions, or paid unlocks
- Banner ads (Google AdMob) are displayed at the bottom of the screen
- You can opt out of the use of advertising IDs (AAID) in your Android system settings

[Recommended for:]
- Students studying fluid dynamics in physics classes
- Those who want to intuitively understand the properties of flow
- Teachers who want to use it as teaching material
- Those interested in aeronautical engineering or fluid dynamics