English: the theorem that, for incompressible and inviscid potential flow, the drag force is 0 on a body moving with constant velocity relative to the fluid, in contradiction to real life, where viscosity causes substantial drag, especially at high velocities
Japanese: 静止している理想流体中に物体を等速直線運動させたときに、物体には抵抗力が働かないという、一見直感に反する事実のこと