流りゅう体たい力りき学がく

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Meanings

fluid mechanics; fluid dynamics; hydrodynamics

Technical term used in physics and engineering. Covers the study of fluids (liquids and gases) in motion and at rest.

流りゅう体たい
流体 means 'fluid' (noun), while 流体力学 is the scientific study of fluids.
力りき学がく
力学 means 'mechanics' in general; 流体力学 is a specific branch dealing with fluids.
水すい力りき学がく
水力学 (hydraulics) focuses on liquids, especially water, whereas 流体力学 covers both liquids and gases.

Compound of 流体 (fluid) and 力学 (mechanics). The term is a direct conceptual borrowing from Western science, likely coined in the Meiji period.