Potential flows of incompressible fluids admit a pressure (Bernoulli) equation when the divergence of the stress is a gradient as in inviscid fluids, viscous fluids, linear viscoelastic fluids and second-order fluids. We show that in potential flow without boundary layers the equation balancing drag and acceleration is the same for all these fluids, independent of the viscosity or any viscoelas...

Consider a three-dimensional vortex sheet in inviscid, incompressible flow which is irrotational away from the sheet. We derive an equation for the evolution of a vortex sheet in Lagrangian coordinates, i.e. an equation that is restricted to the sheet itself and is analogous to the Birkhoff-Rott equation for a two-dimensional (planar) sheet. This general equation is specialized to sheets with a...

research in convective heat transfer using suspensions of nanometer-sized solid particles in base liquids started only over the past decade. recent investigations on nanofluid, as such suspensions are often called, indicate that the suspended nanoparticles remarkably change the transport properties and heat transfer characteristics of the suspension. bending walls can also improve heat transfer...

Free-streamline theory is employed to construct an exact steady solution for a linear array of hollow, or stagnant cored, vortices in an inviscid incompressible fluid. If each vortex has area A and the separation is L, there are two possible shapes if A*/L is less than a critical value 0.38 and none if it is larger. The stability of the shapes to two-dimensional, periodic and symmetric disturba...

The steady state solution of the Euler equations of inviscid ow is computed by an adaptive method. The grid is structured and is re ned and coarsened in prede ned blocks. The equations are discretized by a nite volume method. Error equations, satis ed by the solution errors, are derived with the discretization error as the driving right hand side. An algorithm based on the error equations is de...

We give lower bounds for the lifespan of a solution to the inviscid Boussinesq system. In dimension two, we point out that it tends to infinity when the initial (relative) temperature tends to zero. This is, to the best of our knowledge, the first result of this kind for the inviscid Boussinesq system. In passing, we provide continuation criteria (of independent interest) in the N -dimensional ...

We prove that the essential spectrum of the operator obtained by linearization about a steady state of the Euler equations governing the motion of inviscid ideal fluid in dimension two is a vertical strip whose width is determined by the maximal Lyapunov exponent of the flow induced by the steady state.

A phenomenological theory is proposed to analyze the asymptotic dynamics of perturbed inviscid Kolmogorov shear flows in two dimensions. The phase diagram provided by the theory is in qualitative agreement with numerical observations, which include three phases depending on the aspect ratio of the domain and the size of the perturbation: a steady shear flow, a stationary dipole, and four travel...

Purpose – The aim of the present study is to evaluate the accuracy and efficiency of Lattice-BGK (LBGK) method application in simulation of the 3D flow through complex geometry. On the other hand, the steady flows through vascular tube with Reynolds number 10-150 and different constriction spacing ratios are simulated. Design/methodology/approach – The numerical method is based on the LGBK meth...

In this paper, some ideas for solving Navier-Stokes equations using fractional step techniques in combination with domain decomposition methods are introduced. Apart from its traditional use in a rational distribution of the computational work, the domain decomposition (DD) method can be a powerful tool when dealing with complex geometries, which can have moving parts. The CBS (Characteristic B...