Lateral Force and Yaw Moment on a Slender Body in Forward Motion at a Yaw Angle

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Ronald W. Yeung ◽  
Robert K. M. Seah ◽  
John T. Imamura
Keyword(s):  
Viscous Flow ◽  
Cross Flow ◽  
Slender Body ◽  
Order Effects ◽  
Forward Motion ◽  
Slender Body Theory ◽  
Flow Equations ◽  
The Cross ◽  
Yaw Angle ◽  
Body Theory

This paper presents a solution method for obtaining the lateral hydrodynamic forces and moments on a submerged body translating at a yaw angle. The method is based on the infinite-fluid formulation of the free-surface random-vortex method (FSRVM), which is reformulated to include the use of slender-body theory. The resulting methodology is given the name: slender-body FSRVM (SB-FSRVM). It utilizes the viscous-flow capabilities of FSRVM with a slender-body theory assumption. The three-dimensional viscous-flow equations are first shown to be reducible to a sequence of two-dimensional viscous-fluid problems in the cross-flow planes with the lowest-order effects from the forward velocity included in the cross-flow plane. The theory enables one to effectively analyze the lateral forces and yaw moments on a body undergoing prescribed forward motion with the possible occurrence of cross-flow separation. Applications are made to several cases of body geometry that are in steady forward motion, but at a yawed orientation. These include the case of a long “cone-tail” body. Comparisons are made with existing data where possible.

Separated Flow About a Slender Body in Forward and Lateral Motion

2008 ◽  
Author(s):  
Ronald W. Yeung ◽  
Robert K. M. Seah ◽  
John T. Imamura
Keyword(s):  
Viscous Flow ◽  
Cross Flow ◽  
Separated Flow ◽  
Vortex Method ◽  
Slender Body ◽  
Order Effects ◽  
Forward Motion ◽  
Slender Body Theory ◽  
Flow Equations ◽  
Body Theory

This paper presents a solution method for obtaining the hydrodynamic forces and moments on a submerged body translating at a yaw angle. The method is based on the infinite-fluid formulation of the Free Surface Random Vortex Method (FSRVM), which is re-formulated to include the use of slender-body theory. The resulting methodology is given the name: Slender-Body FSRVM (SB-FSRVM). It utilizes the viscous-flow capabilities of FSRVM with a slender-body theory assumption. The three-dimensional viscous-flow equations are first shown to be reducible to a sequence of two-dimensional viscous-fluid problems in the cross-flow planes with the lowest-order effects from the forward velocity included. The theory enables one to analyze effectively the lateral forces and yaw moments on a body undergoing prescribed forward motion with the possible occurrence of flow separation. Applications are made to several cases of body geometry that are in steady forward motion, but at a yawed orientation. These include the case of a long “cone-tail” body. Comparisons are made with existing data where possible.

Two-Dimensional Apparent Masses for Cross-Flow Sections of Wing-Store Configurations

1982 ◽  
Vol 49 (3) ◽  
pp. 471-475
Author(s):  
M.-K. Huang
Keyword(s):  
Approximate Method ◽  
Cross Flow ◽  
Slender Body ◽  
Two Dimensional ◽  
Aerodynamic Stability ◽  
Slender Body Theory ◽  
Rolling Moment ◽  
Stability Derivatives ◽  
The Cross ◽  
Body Theory

On the basis of the assumption that the external stores are small compared with the wing, an approximate method has been developed for estimation of two-dimensional apparent masses for the cross-flow sections of wing-store combinations. The results obtained may be applicable to the analysis of the effects of the stores on the aerodynamic stability derivatives in slender-body theory. The theory has also been applied to estimate the rolling moment due to sideslip for high-wing configurations. The presented results are in agreement with those of other investigations.

Cowl Shapes of Minimum Drag in Supersonic Flow

1965 ◽  
Vol 69 (649) ◽  
pp. 46-48 ◽  
Author(s):  
E. Angus Boyd
Keyword(s):  
Slender Body ◽  
Control Surface ◽  
Axially Symmetric ◽  
Slender Body Theory ◽  
Flow Equations ◽  
Pressure Drag ◽  
Minimum Drag ◽  
Impact Theory ◽  
Body Theory ◽  
External Stream

Guderley, Armitage and Valentine have computed the inlet and closed body contours which form the forepart of an axially symmetric body, of given length and fineness ratio, having minimum pressure drag. The solution is not based on a simplified pressure law, such as the Newtonian impact law, because by a suitable choice of control surface for mass flow and momentum they are able to employ the general flow equations. It is clear, however, from an analysis of their tabulated results that their cowl shapes fall on a single curve for a given value of Δ=didt, the ratio of the initial to the final diameter of the cowl, when plotted in terms of a dimensionless length ξ=x/l and thickness η=y/dt, as in Fig. 1. Furthermore Fig. 1 shows that, except for small values of Δ, the Guderley shapes are indistinguishable from the optimum shapes calculated from Newtonian impact theory. The shape and characteristics of the Newtonian duct of given length and thickness, offering minimum drag to the external stream, are derived using the slender-body approximation. Ducts for which Δ > 0.04 are shown to be sufficiently slender. The slopes of those with 0 ≤ Δ < 0.04 are too large only in a small critical region near the nose. Thus slender body theory will give a close approximation to the exact Newtonian solution even in these cases. For the larger values of Δ likely to be used in practice slender body theory is valid everywhere.

Sway, Roll, and Yaw Motion Coefficients Based on a Forward-Speed Slender-Body Theory—Part 1

1981 ◽  
Vol 25 (01) ◽  
pp. 8-15
Author(s):  
Armin Walter Troesch
Keyword(s):  
Cross Coupling ◽  
Added Mass ◽  
Numerical Results ◽  
Slender Body ◽  
Forward Speed ◽  
Coupling Coefficients ◽  
Slender Body Theory ◽  
Damping Coefficients ◽  
The Cross ◽  
Body Theory

The added-mass and damping coefficients for sway, roll, and yaw are formulated for a ship with forward speed. The theory is similar to that given by Ogilvie and Tuck (1969) for the heave and pitch coefficients of a slender ship. Numerical results are presented for the cross-coupling coefficients.

Note on the swimming of slender fish

1960 ◽  
Vol 9 (2) ◽  
pp. 305-317 ◽  
Author(s):  
M. J. Lighthill
Keyword(s):  
Swimming Speed ◽  
Critical Value ◽  
Slender Body ◽  
Vortex Wake ◽  
Frictional Drag ◽  
Slender Body Theory ◽  
Propulsive Efficiency ◽  
Deformable Bodies ◽  
Work Done ◽  
Body Theory

The paper seeks to determine what transverse oscillatory movements a slender fish can make which will give it a high Froude propulsive efficiency, $\frac{\hbox{(forward velocity)} \times \hbox{(thrust available to overcome frictional drag)}} {\hbox {(work done to produce both thrust and vortex wake)}}.$ The recommended procedure is for the fish to pass a wave down its body at a speed of around $\frac {5} {4}$ of the desired swimming speed, the amplitude increasing from zero over the front portion to a maximum at the tail, whose span should exceed a certain critical value, and the waveform including both a positive and a negative phase so that angular recoil is minimized. The Appendix gives a review of slender-body theory for deformable bodies.

Slender-body theory for slow viscous flow

1976 ◽  
Vol 75 (4) ◽  
pp. 705-714 ◽  
Author(s):  
Joseph B. Keller ◽  
Sol I. Rubinow
Keyword(s):  
Integral Equation ◽  
Incompressible Fluid ◽  
Viscous Incompressible Fluid ◽  
Unit Length ◽  
The Body ◽  
Slender Body ◽  
Slow Flow ◽  
Slender Body Theory ◽  
Slow Viscous Flow ◽  
Body Theory

Slow flow of a viscous incompressible fluid past a slender body of circular crosssection is treated by the method of matched asymptotic expansions. The main result is an integral equation for the force per unit length exerted on the body by the fluid. The novelty is that the body is permitted to twist and dilate in addition to undergoing the translating, bending and stretching, which have been considered by others. The method of derivation is relatively simple, and the resulting integral equation does not involve the limiting processes which occur in the previous work.

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