Boson Hamiltonians and stochasticity for the vorticity equation

1990 ◽  
Vol 68 (9) ◽  
pp. 719-722 ◽  
Author(s):  
Hubert H. Shen
Keyword(s):  
Viscous Flow ◽  
Inviscid Flow ◽  
Vorticity Equation ◽  
Hamiltonian Form ◽  
Bose Operators

The evolution of the vorticity in time for 2D inviscid flow and in Lagrangian time for 3D viscous flow is written in Hamiltonian form by introducing Bose operators. The addition of the viscous and convective terms, respectively, leads to an interpretation of the Hamiltonian contribution to the evolution as Langevin noise.

scholarly journals Computation of Secondary Flows in an Axial Flow Compressor Including Inviscid and Viscous Flow Computation

1984 ◽  
Author(s):  
Francis Leboeuf
Keyword(s):  
Boundary Layer ◽  
Viscous Flow ◽  
Axial Flow ◽  
Inviscid Flow ◽  
Secondary Flows ◽  
Computational Method ◽  
Flow Computation ◽  
Axial Flow Compressor ◽  
Flow Compressor ◽  
Highly Loaded

A computational method for secondary flows in a compressor has been extended to treat stalled flows. An integral equation is used which simulates the inviscid flow at the wall, under the viscous flow influence. We present comparisons with experimental results for a 2D stalled boundary layer, and for the secondary flow in a highly loaded stator of an axial flow compressor.

Computation of Viscous Flow Around Propeller-Body Configurations: Series 60 CB = 0.6 Ship Model

1994 ◽  
Vol 38 (02) ◽  
pp. 137-157 ◽  
Author(s):  
F. Stern ◽  
H. T. Kim ◽  
D. H. Zhang ◽  
Y. Toda ◽  
J. Kerwin ◽  
...  
Keyword(s):  
Viscous Flow ◽  
Turbulence Modeling ◽  
Critical Evaluation ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Ship Model ◽  
Flow Method ◽  
Critical Issues ◽  
Three Dimensional Configuration ◽  
Extensive Experimental Data

Validation of a viscous-flow method for predicting propeller-hull interaction is provided through detailed comparisons with recent extensive experimental data for the practical three-dimensional configuration of the Series 60 CB = 0.6 ship model. Modifications are made to the k-e turbulence model for the present geometry and application. Agreement is demonstrated between the calculations and global and some detailed aspects of the data; however, very detailed resolution of the flow is lacking. This supports the previous conclusion for propeller-shaft configurations and axisymmetric bodies that the present procedures can accurately simulate the steady part of the combined propeller-hull flow field, although turbulence modeling and detailed numerical treatments are critical issues. The present application enables a more critical evaluation through further discussion of these and other relevant issues, such as the use of radial-and angular-varying body-force distributions, the relative importance of turbulence modeling and grid density on the resolution of the harmonics of the propeller inflow, and three-dimensional propeller-hull interaction, including the differences for the nominal and effective inflows and for the resulting steady and unsteady propeller performance. Also, comparisons are made with an inviscid-flow method. Lastly, some concluding remarks are made concerning the limitations of the method, requirements and prognosis for improvements, and application to the design of wake-adapted propellers.

Calculations of Three-Dimensional, Viscous Flow and Wake Development in a Centrifugal Impeller

1981 ◽  
Vol 103 (2) ◽  
pp. 367-372 ◽  
Author(s):  
J. Moore ◽  
J. G. Moore
Keyword(s):  
Viscous Flow ◽  
Pressure Field ◽  
Three Dimensional ◽  
Inviscid Flow ◽  
Calculation Procedure ◽  
Wake Flow ◽  
Centrifugal Impeller ◽  
Duct Flow ◽  
Reduced Pressure ◽  
Flow Calculation

A partially-parabolic calculation procedure is used to calculate flow in a centrifugal impeller. This general-geometry, cascade-flow method is an extension of a duct-flow calculation procedure. The three-dimensional pressure field within the impeller is obtained by first performing a three-dimensional inviscid flow calculation and then adding a viscosity model and a viscous-wall boundary condition to allow calculation of the three-dimensional viscous flow. Wake flow, resulting from boundary layer accumulation in an adverse reduced-pressure gradient, causes blockage of the impeller passage and results in significant modifications of the pressure field. Calculated wake development and pressure distributions are compared with measurements.

Numerical Simulation of the Flow Around an Array of Free-Surface Piercing Cylinders in Waves

2007 ◽  
Author(s):  
Roberto Muscari ◽  
Andrea Di Mascio ◽  
Riccardo Broglia
Keyword(s):  
Numerical Simulation ◽  
Free Surface ◽  
Viscous Flow ◽  
Wave Height ◽  
Inviscid Flow ◽  
Incoming Wave ◽  
An Array Of Cylinders

This work deals with the viscous flow around an array of cylinders impinged by an incoming wave. Different configurations are considered in order to evaluate the effects of both wave heading and wave height on the loads applied to the bodies and on the run-ups. The results are also compared to previous calculations obtained with the assumption of inviscid flow with the aim of evaluating the contribution of viscosity.

Viscid-Inviscid Interaction of Incompressible Separated Flows

1976 ◽  
Vol 43 (3) ◽  
pp. 387-395 ◽  
Author(s):  
W. L. Chow ◽  
D. J. Spring
Keyword(s):  
Viscous Flow ◽  
Pressure Coefficient ◽  
Separated Flow ◽  
Inviscid Flow ◽  
Turbulent Jet ◽  
Tunnel Wall ◽  
Flow Process ◽  
Jet Mixing ◽  
Flow Problems ◽  
Flow Components

A flow model has been devised to deal with the viscid-inviscid interaction of a class of two-dimensional incompressible separated flow problems. It is suggested that the corresponding inviscid flow of these problems is described by the free streamline theory with few unspecified parameters and their values are, in turn, determined by the viscous flow considerations. The problem of a flow past a backward facing step is selected for study in detail. The viscous flow components of turbulent jet mixing, recompression, and reattachment are delineated and studied individually. When they are later combined, it is found that the point of reattachment behaves as a saddle-point-type singularity in the system of differential equations describing the viscous flow process. This feature is employed to the determination of the aforementioned free parameters and thus the establishment of the overall corresponding inviscid flow field. The resulting base pressure coefficient for the specific case agrees reasonably well with the available experimental data. Additional calculations are performed to demonstrate the influence of higher Reynolds numbers and the values of the similarity (or spread rate) parameter σ of the “constant pressure” turbulent jet mixing process. Further studies of redevelopment of the viscous flow after reattachment, the turbulent exchange within the recompression and redevelopment regions, and the effect of wind tunnel-wall interference on the overall flow patterns have been suggested and discussed.

Viscous Flow and Inviscid Flow-Connections and Interactions

2014 ◽  
pp. 107-130
Author(s):  
Ernst Heinrich Hirschel ◽  
Jean Cousteix ◽  
Wilhelm Kordulla
Keyword(s):  
Viscous Flow ◽  
Inviscid Flow

The final approach to steady, viscous flow near a stagnation point following a change in free stream velocity

1962 ◽  
Vol 13 (3) ◽  
pp. 449-464 ◽  
Author(s):  
R. E Kelly
Keyword(s):  
Viscous Flow ◽  
Stagnation Point ◽  
Leading Edge ◽  
Inviscid Flow ◽  
Stream Velocity ◽  
Two Dimensional ◽  
Axially Symmetric ◽  
Plane Normal ◽  
Final Approach ◽  
Linear Differential

The flow field near a stagnation point in two-dimensional, incompressible, viscous flow is considered to change with time in such a way that the inviscid flow is steady after some given finite instant of time. The final approach to steady flow throughout the field is shown to be characterized by exponential decay with time of perturbations from the steady velocity field. The characteristic factors in the exponents arise from the solution of an eigenvalue problem in ordinary linear differential equations.Similar behaviour exists for the axially symmetric case. A comparable analysis furnishes, however, a meaningless result in the case of a two-dimensional, semiinfinite flat plate which is moving in its own plane, normal to its leading edge.

scholarly journals Integrals of the Vorticity Equation. Part II: Special Two-Dimensional Flows

2006 ◽  
Vol 63 (2) ◽  
pp. 611-616 ◽  
Author(s):  
Robert Davies-Jones
Keyword(s):  
Shear Flow ◽  
Formal Solution ◽  
Inviscid Flow ◽  
Vorticity Equation ◽  
Two Dimensional ◽  
General Integral ◽  
2D Flow ◽  
Stratified Shear Flow ◽  
Two Dimensional Flows

Abstract In Part I, a general integral of the 2D vorticity equation was obtained. This is a formal solution for the vorticity of a moving tube of air in a 2D unsteady stratified shear flow with friction. This formula is specialized here to various types of 2D flow. For steady inviscid flow, the integral reduces to an integral found by Moncrieff and Green if the flow is Boussinesq and to one obtained by Lilly if the flow is isentropic. For steady isentropic frictionless motion of clear air, several quantities that are invariant along streamlines are found. These invariants provide another way to obtain Lilly’s integral from the general integral.

A study of two-dimensional flow past regular polygons via conformal mapping

2009 ◽  
Vol 628 ◽  
pp. 121-154 ◽  
Author(s):  
ZHONG WEI TIAN ◽  
ZI NIU WU
Keyword(s):  
Reynolds Number ◽  
Circular Cylinder ◽  
Viscous Flow ◽  
Strouhal Number ◽  
Bifurcation Point ◽  
Critical Reynolds Number ◽  
Inviscid Flow ◽  
Two Dimensional ◽  
Regular Polygons ◽  
Two Dimensional Flow

In this paper we study two-dimensional flow around regular polygons with an arbitrary but even number of edges N and one apex pointing to the free stream, with comparison to circular-cylinder flow. Both inviscid flow and low-Reynolds-number viscous flow are addressed. For inviscid flow, we obtained the exact solution for pure potential flow through Schwarz–Christoffel transformation, with the emphasis on the role of edge number, N, on the flow details. We also studied the behaviour, stationary lines and stability of vortex pair and found new stationary lines compared to circular cylinder. For viscous flow we derived the equation of stream function in the mapped (circle) domain, based on which approximate expressions for the critical Reynolds numbers and Strouhal number, as functions of the edge number, are obtained. The Reynolds number is based on the diameter of the circumscribed circle. For the steady flow, the first critical Reynolds number is a monotonically decreasing function of N, while N → ∞ corresponds to that for circular cylinder. The bifurcation point is ahead of the bifurcation point for circular cylinder. For unsteady flow, the critical Reynolds number for vortex shedding and the Strouhal number are both monotonically decreasing functions of N.

Viscous flow near a cusped corner

1967 ◽  
Vol 27 (4) ◽  
pp. 647-656 ◽  
Author(s):  
G. Schubert
Keyword(s):  
Boundary Value Problem ◽  
Boundary Conditions ◽  
Viscous Flow ◽  
Asymptotic Form ◽  
Boundary Value ◽  
Slow Motion ◽  
Inviscid Flow ◽  
Uniform Shear ◽  
The Moment

The slow motion of fluid exterior to a cylinder lying on a wall is considered for a variety of boundary conditions. In particular, the solution is obtained for the case when the motion far from the cylinder is one of uniform shear. Calculations are made for the force and the moment exerted by the fluid on the cylinder. The asymptotic form of the flow both far from the cylinder and near the cusped corners is presented. The flow sufficiently near a cusp consists of a sequence of eddies of rapidly diminishing strength, and the solution of another boundary-value problem supports the view that the nature of this eddy system is independent of conditions far from the cusp. The nature of inviscid flow with uniform vorticity in cusped corners is also considered.

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