Research on the Improved Body-Force Method Based on Viscous Flow

Abstract The virtual propeller model can achieve the rapid numerical prediction of the ship self-propulsion performance through viscous flow, which used the improved body-force method. The two-dimensional lift coefficient CL and the drag coefficient CD are very important parameters in this method, which are generally obtained by the potential flow methods and cannot incorporate viscous effects. This study will perform a fully nonlinear unsteady RANS (Reynolds Average Navier-Stokes) simulation to get the KP505 open-water characteristics and then divide its blade into several parts to get the lift coefficient CL and the drag coefficient CD on each one. Then fitting by multivariate regression method, the relationship between CL, CD and propeller parameters is obtained. The Unsteady Blade Element Theory (UBET) is coupled with RANS in house CFD code HUST-Ship (Hydrodynamic Unsteady Simulation Technology for Ship) to calculate the flow around the propeller. RANS equations are solved by the finite difference method and PISO arithmetic. have been made using structured grid with overset technology. The results show that comparing with the EFD data, the maximum differences of the result of the improved body-force method are 4.32% and 2.7% for the thrust coefficient and the torque coefficient respectively near the propeller operating point.

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The solution of the dynamic field of the Haskell fault model reconsidered

Bulletin of the Seismological Society of America ◽

10.1785/bssa0720041069 ◽

1982 ◽

Vol 72 (4) ◽

pp. 1069-1083

Author(s):

R. D. List

Keyword(s):

Half Space ◽

Displacement Field ◽

Body Force ◽

Fault Model ◽

Earthquake Source ◽

Infinite Space ◽

Force Method ◽

Body Force Method ◽

Rupture Speed ◽

Seismic Dislocations

abstract A method of obtaining the displacement field of the Haskell model of an earthquake source, based on the well-known equivalence of seismic dislocations and body force, is described. It is shown that the solution of Madariaga (1978) can be generalized and that the two methods are equivalent for the problem of a rectangular dislocation expanding on a plane in an infinite space with a variable rupture speed and variable slip in the direction of rupture. One of the advantages of the equivalent body force method is that it can be used to readily obtain the transformed solution to the Haskell model in a half-space for a rectangular dislocation, expanding with variable rupture speed and variable slip.

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Accurate Solutions of Stress Intensity Factors of Standard Fracture Test Specimens

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.452-453.405 ◽

2010 ◽

Vol 452-453 ◽

pp. 405-408 ◽

Cited By ~ 1

Author(s):

Akihide Saimoto ◽

Fumitaka Motomura ◽

Hironobu Nisitani

Keyword(s):

Stress Intensity ◽

Body Force ◽

General Purpose ◽

Two Dimensional ◽

Fracture Test ◽

Intensity Factors ◽

Force Method ◽

Body Force Method ◽

Standard Specimens ◽

Significant Figures

Practically exact solutions of stress intensity factor for several two-dimensional standard specimens were calculated and shown in numeric tables. The solutions were confirmed to converge until 6 significant figures through a systematical computation of discretization analysis. The convergence analyses were carried out by using a general purpose program based on a body force method.

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Assessment Procedure for Multiple Volumetric Flaws in p-M Diagram

Journal of Pressure Vessel Technology ◽

10.1115/1.3110036 ◽

2009 ◽

Vol 131 (3) ◽

Cited By ~ 3

Author(s):

Shinji Konosu

Keyword(s):

Body Force ◽

Pressure Vessels ◽

The Body ◽

Assessment Procedure ◽

Force Method ◽

Reference Stress ◽

Body Force Method ◽

Common Problems ◽

Shielding Effects

Assessment of multiple volumetric flaws is one of the most common problems relating to pressure vessels and piping components. Under the current fitness for service rules, such as ASME, BS, and so on, multiple volumetric flaws are usually recharacterized as an enveloping volumetric flaw (defined as a single larger volumetric flaw) as well as multiple cracklike flaws, following their assessment rules. However, the rules proposed in their codes will not often agree and their justification is unknown. Furthermore, they can provide unrealistic assessment in some cases. In this paper, the interaction between two differently sized nonaligned volumetric flaws such as local thin areas is clarified by applying the body force method. Unlike multiple cracklike flaws, the effect of biaxial stresses on the interaction is evident. Based on the interaction that indicates the magnification and shielding effects and reference stress solutions, a new procedure for multiple volumetric flaws is proposed for assessing the flaws in the p-M (pressure-moment) diagram, which is a simple assessment procedure for vessels with volumetric flaws.

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