【单选题】73 / 88黏性不可压缩均质流体的运动方程是Aρdvdt=ρF−gradp+μ∇2v\rho\frac{d\boldsymbol{v}}{dt}=\rho\boldsymbol{F}-\operatorname{grad}p+\mu\nabla^2\boldsymbol{v}ρdtdv=ρF−gradp+μ∇2v正确Bρdvdt=ρF−gradp\rho\frac{d\boldsymbol{v}}{dt}=\rho\boldsymbol{F}-\operatorname{grad}pρdtdv=ρF−gradpCρdvdt=ρF+divP\rho\frac{d\boldsymbol{v}}{dt}=\rho\boldsymbol{F}+\operatorname{div}\boldsymbol{P}ρdtdv=ρF+divPDρdvdt=ρF−gradp+μ∇2v+μ3graddivv\rho\frac{d\boldsymbol{v}}{dt}=\rho\boldsymbol{F}-\operatorname{grad}p+\mu\nabla^2\boldsymbol{v}+\frac{\mu}{3}\operatorname{grad}\operatorname{div}\boldsymbol{v}ρdtdv=ρF−gradp+μ∇2v+3μgraddivv参考答案A参考解析divv=0\operatorname{div}\boldsymbol{v}=0divv=0 时 N-S 方程简化为 ρdvdt=ρF−gradp+μ∇2v\rho\frac{d\boldsymbol{v}}{dt}=\rho\boldsymbol{F}-\operatorname{grad}p+\mu\nabla^2\boldsymbol{v}ρdtdv=ρF−gradp+μ∇2v(K3−52K3-52K3−52)。