Search results for "Potential flow"

Mathematical description of the stimuli to the lateral line system of fish derived from a three-dimensional flow field analysis

1992

The spatial distributions of the stimuli to the lateral line system of a fish moving alongside or above a plane surface are derived mathematically. The derivation was done from the analysis of the three-dimensional potential flow field on the surface of fish with bodies of circular cross-section with different shapes.

Stability of a Tensioned Axially Moving Plate Subjected to Cross-Direction Potential Flow

2015

We analyze the stability of an axially moving Kirchhoff plate, subjected to an axial potential flow perpendicular to the direction of motion. The dimensionality of the problem is reduced by considering a cross-directional cross-section of the plate, approximating the axial response with the solution of the corresponding problem of a moving plate in vacuum. The flow component is handled via a Green’s function solution. The stability of the cross-section is investigated via the classical Euler type static linear stability analysis method. The resulting eigenvalue problem is solved numerically using Hermite type finite elements. As a result, the critical velocity and the corresponding eigenfun…

LES of the flow around two cylinders in tandem

2008

The flow around an arrangement of two-in-tandem cylinders exhibits a remarkably\ud complex behaviour that is of interest for many engineering problems, such as environmental\ud flows or structural design. In the present paper, a Large Eddy Simulation using a staggered\ud Cartesian grid has been performed for the flow around two-in-tandem cylinders of diameter\ud D=20mm and height H=50mm submerged in an open channel with height h=60 mm. The two\ud axes have a streamwise spacing of 2D. The Reynolds number is 1500, based on the cylinder\ud diameter and the free-stream velocity u�. The results obtained show that no vortex shedding\ud occurs in the gap between the two cylinders where the separat…

BEM Formulation of the Trailing Edge Condition

1995

This paper deals with a BEM formulation of the trailing edge condition to determine the potential flow field around an airfoil. It is seen the trailing edge condition is not sufficient to give an unique solution. It is necessary to assign a further condition to eliminate the nonuniqueness of the solution. The approach allows to adopt a discretization into superior order elements. Some preliminary applications show the validity of the formulation.

Travelling Panels Interacting with External Flow

2013

This chapter is devoted to the analysis of the travelling panel, submerged in axially flowing fluid. In order to accurately model the dynamics and stability of a lightweight moving material, the interaction between the material and the surrounding air must be taken into account somehow. The light weight of the material leads to the inertial contribution of the surrounding air to the acceleration of the material becoming significant. In the small displacement regime, the geometry of the vibrating panel is approximately flat, and hence flow separation is unlikely. We will use the model of potential flow for the fluid. The approach described in this chapter allows for an efficient semi-analyti…

Analysis of complex singularities in high-Reynolds-number Navier-Stokes solutions

2013

AbstractNumerical solutions of the laminar Prandtl boundary-layer and Navier–Stokes equations are considered for the case of the two-dimensional uniform flow past an impulsively-started circular cylinder. The various viscous–inviscid interactions that occur during the unsteady separation process are investigated by applying complex singularity analysis to the wall shear and streamwise velocity component of the two solutions. This is carried out using two different methodologies, namely a singularity-tracking method and the Padé approximation. It is shown how the van Dommelen and Shen singularity that occurs in solutions of the Prandtl boundary-layer equations evolves in the complex plane be…

The lift computation for an oscillating flat plate in incompressible potential flow

1994

The initial aim of this work was the estimation of the lift acting on a flat plate performing small oscillations in a plane uniform stream by means of a simplified model based on one or at the most two lumped vortices, and the assessment of its results by comparison to those that were exact. The model was found to work well up to a reduced frequency of about 1 or 2, above which the results diverged from those that were correct. In order to improve the model, its behaviour at very high frequencies was then investigated, discovering: (i) that if the number of lumped vortices is greater than one the possibility to impose all boundary conditions is subject to certain geometrical constraints; (i…

CFD analysis of the fluid flow behavior in a reverse electrodialysis stack

2012

Salinity Gradient Power by Reverse Electrodialysis (SGP-RE) technology allows the production of electricity from the different chemical potentials of two differently concentrated salty solutions flowing in alternate channels suitably separated by selective ion exchange membranes. In SGP-RE, as well as in conventional ElectroDialysis (ED) technology, the process performance dramatically depends on the stack geometry and the internal fluid dynamics conditions: optimizing the system geometry in order to guarantee lower pressure drops (DP) and uniform flow rates distribution within the channels is a topic of primary importance. Although literature studies on Computational Fluid Dynamics (CFD) a…

On the mechanical stability and out-of-plane dynamics of a travelling panel submerged in axially flowing ideal fluid : a study into paper production …

2011

Computation of vertically averaged velocities in irregular sections of straight channels

2015

Abstract. Two new methods for vertically averaged velocity computation are presented, validated and compared with other available formulas. The first method derives from the well-known Huthoff algorithm, which is first shown to be dependent on the way the river cross section is discretized into several subsections. The second method assumes the vertically averaged longitudinal velocity to be a function only of the friction factor and of the so-called "local hydraulic radius", computed as the ratio between the integral of the elementary areas around a given vertical and the integral of the elementary solid boundaries around the same vertical. Both integrals are weighted with a linear shape f…