Water-hammer is a transient condition which may occur in a network as a result of rapid or slow valve closures, pump failures, changes in turbine loading, etc. It creates high and low pressure waves which travel along the system and decay as a result of wall shear stress. Comparison o experimental and theoretical results revealed the failure of steady or quasi-steady models in correctly predict...

the effect of weak shear thickening and shear thinning on the stability of the taylor-couette flow is explored for a carreau-bird fluid in the narrow-gap limit. the galerkin projection method is used to derive a low-order dynamical system from the conservation of mass and momentum equations. in comparison with the newtonian system, the present equations include additional nonlinear coupling in ...

a two dimensional finite difference lattice boltzmann method (fdlbm) for computing single phase flow problems is developed here. temporal term is discretized with low dissipation-low dispersion. discretization of convective term is implemented with third order upwind method. it will be explained governing equations and numerical method. methodology of imposing boundary conditions in fdlbm is de...

Time-dependent flows of a Newtonian fluid through periodic arrays of spheres were simulated using the lattice-Boltzmann scheme. By applying a constant body force per unit mass to the fluid, a steady background fluid flow through the array of stationary spheres was first established. Subsequently, a small-amplitude perturbation to the body force, which varied periodically in time, was added and ...

This paper presents an adjoint method for the optimum shape design of unsteady flows. The goal is to develop a set of discrete unsteady adjoint equations and the corresponding boundary condition for the non-linear frequency domain method. First, this paper presents the complete formulation of the time dependent optimal design problem. Second, we present the non-linear frequency domain adjoint e...

The present investigation examines the suppression of unsteady, two-dimensional wake instabilities of a pair of identical circular cylinders, placed side-by-side normal to freestream at a low Reynolds number of 150. It is found that when the cylinders are counter-rotated, unsteady vortex wakes can be completely suppressed. At fast enough rotational speeds, a virtual elliptic body is produced by...

A hardware-based approach for visualizing unsteady flow fields by means of Lagrangian-Eulerian advection is presented. Both noise-based and dyebased texture advection is supported. The implementation allows the advection of each texture to be performed completely on the graphics hardware in a single-pass rendering. We discuss experiences with the interactive visualization of unsteady flow field...

This paper presents experiments with a new algorithm for the unseady (tranient) thrust control bladed-propeller marine thrusters. Comparative experiments over a wide range of unsteady operating conditions with three different thrust control algorithms demonstrate the model-based control algorithm to offer transient thrust-control performance superior to that of its non-model-based counterpart. ...

Statistical flow modelling does not provide enough detail for many flows of engineering relevance in which unsteadiness is a central feature. This applies particularly to bluff-bodies and assemblies comprising bluff components for which the resolution of peak forces, unsteady loading, acoustics and fatigue are of interest as part of the design process. An example application which has been stud...

Lin & Pauley [2] studied unsteady boundary-layer separation from an Eppler 387 airfoil at low Reynolds number numerically and compared their results with wind tunnel measurements. They found unsteady large-scale structure might control the lowReynolds-number separation bubble reattachment with smallscale turbulence playing a secondary role [4]. Drela [5], Drela & Giles[6] used a fully coupled n...