====== オイラー方程式 ======
==== Euler's equation ====

{{tag>..c09}}

　粘性のない流体の運動を記述する方程式．二次元非圧縮性流体の場合\[\begin{array}{l} \frac{{\partial u}}{{\partial t}} + u\frac{{\partial u}}{{\partial x}} + v\frac{{\partial u}}{{\partial y}} =  - \frac{1}{\rho }\frac{{\partial p}}{{\partial x}}\\ \frac{{\partial v}}{{\partial t}} + u\frac{{\partial v}}{{\partial x}} + v\frac{{\partial v}}{{\partial y}} =  - \frac{1}{\rho }\frac{{\partial p}}{{\partial y}} \end{array}\]ここで（//u//, //v//）は直角座標（//x//, //y//）方向の速度を，//p//は圧力，//ρ//は密度（一定），//t//は時間を表す．


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