1. Steady flow and unsteady flow(1) Steady flow is the flow whose motion factors (such as flow,density,pressureand viscosity) don’t change with time. That is:So acceleration of euler at constant flow is a=(μ·▽)u.(2) Unsteady flow is the flow that at least...[继续阅读]

    Three types of curves are commonly used to describe fluid motion-streamlines,pathlines,and streaklines. These are defined and described here assuming that the fluidvelocity vector,V,is known at every point of space and instant of time throughout theregion...[继续阅读]

    1. StreamtubeConsider a closed curve(not streamline) in the flow field,then draw streamlinesthrough every point on it,so as to form a tube-shaping space whose walls arestreamlines. This tube is called the streamtube(see Fig. 3-7).2. Tube flowFluid fulling...[继续阅读]

    Two important properties of gradually varied flow in cross section:(1) Flow cross-section of gradually varied flow is approximately flat. Direction ofvelocity approximately parallel to each point in cross section.(2) The hydrodynamic pressure of gradually...[继续阅读]

    The particle is micelles,micellar motions were decomposited the Helmholtz.Motion of fluid particle may be subjected to translation,rotation and deformation(including linear deformation and angular deformation). Actually,many movement offluid was combined ...[继续阅读]

    It is antisymmetric so its diagonal elements are zero and its off-diagonal elementsare equal and opposite. Furthermore,its three independent elements can be put incorrespondence with a vector.Defining O: (u,v),A: (uA,vA)dt:SimilarlySoDefiningSimilarly...[继续阅读]

    Rotational flow is also called Vortex flow. The fluid particles of rotational flowrotate about its axis,and is independent of motion path. One of the three components(ωx,ωy,ωz) of the rotation is not zero at least.Rotational flow or irrotational flow depe...[继续阅读]

    1. The general form of basic equation for steady flowTake a six-sided infinitesimal as control body in the flow field,which side lengthare dx,dy,dz. Control body is a designated space in the flow field,its shape,positionfixed so that fluid may not be affe...[继续阅读]

    1. Stress analysisAs can be seen in Fig. 3-12,take a differential element hexahedral with a center (x,y,z) in ideal fluid. Its side length are dx,dy,dz,and its center of pressure is p(x,y,z). Pressure of M,N points are through the center of pressure by Ta...[继续阅读]

    Viscous fluid,also known as the actual fluid. Derivation of differential equations ofmotion of a viscous fluid the same as above,but due to the presence of viscous stressstate than the more complex an ideal fluid. Here will not be detailed derivation,only...[继续阅读]