scholarly journals A fast non-iterative numerical algorithm to predict unsteady partial cavitation on hydrofoils

2013 ◽  
Vol 37 (9) ◽  
pp. 6446-6457 ◽  
Author(s):  
Morteza Behbahani-Nejad ◽  
Maziar Changizian
Keyword(s):  
Numerical Algorithm ◽  
Partial Cavitation ◽  
Iterative Numerical Algorithm

Computer Aided Synthesis of Rational Motion Under Kinematic Constraints of Spatial SS Open Chains

2008 ◽  
Author(s):  
Anurag Purwar ◽  
Zhe Jin ◽  
Q. J. Ge
Keyword(s):  
Numerical Algorithm ◽  
Smooth Curve ◽  
Dual Quaternion ◽  
Open Chain ◽  
End Effector ◽  
Kinematic Constraints ◽  
Constraint Manifold ◽  
Computer Aided ◽  
Quaternion Representation ◽  
Iterative Numerical Algorithm

In this paper, we study the problem of rational motion interpolation under kinematic constraints of spatial SS open chains. The objective is to synthesize a smooth rational motion that interpolates a given set of end effector positions and satisfies the kinematic constraints imposed by spatial SS open chains. The kinematic constraints under consideration define a constraint manifold representing all the positions available to the end effector. By choosing dual quaternion representation for the displacement of the end effector, the problem is reduced to designing a smooth curve in the space of dual quaternions that is constrained to lie inside the constraint manifold of the spatial SS open chain. An iterative numerical algorithm is presented that solves this problem effectively. The results presented in this paper are extension of our previous work on the synthesis of piecewise rational planar and spherical motions for open and closed chains under kinematic constraints.

Generalized pulse‐spectrum technique

Geophysics ◽  
1985 ◽  
Vol 50 (11) ◽  
pp. 1664-1675 ◽  
Author(s):  
Y. M. Chen
Keyword(s):  
Shear Modulus ◽  
Bulk Modulus ◽  
Numerical Algorithm ◽  
Seismic Data ◽  
Nonlinear Partial Differential Equations ◽  
Density Variation ◽  
Adaptive Grids ◽  
Pulse Spectrum ◽  
Uniform Grids ◽  
Iterative Numerical Algorithm

The generalized pulse‐spectrum technique (GPST) is a versatile and efficient iterative numerical algorithm for solving multiparameter inverse problems of a system of nonlinear partial differential equations. Here it is used to determine bulk modulus, shear modulus, and density variation from seismic data. Numerical simulations of simple but nontrivial examples are carried out on coarse uniform grids and adaptive grids to test and to study the general characteristics of GPST without the real measurements (seismograms). GPST does give reasonably good results. It can be made more efficient by implementing parallelism, automatic adaptive‐grids, and methods of domain decomposition into the numerical algorithm.

An iterative scheme for axisymmetric supercavitating flow

2009 ◽  
Vol 223 (8) ◽  
pp. 1869-1876 ◽  
Author(s):  
N M Nouri ◽  
A Eslamdoost
Keyword(s):  
Free Surface ◽  
Flow Field ◽  
Numerical Algorithm ◽  
Numerical Solutions ◽  
Iterative Scheme ◽  
Initial Guess ◽  
Convergence Criterion ◽  
Supercavitating Flow ◽  
Cavity Closure ◽  
Iterative Numerical Algorithm

This article presents a numerical investigation of axisymmetric supercavitating flow. It is assumed that such a flow field could be estimated by a potential flow that neglects the viscosity effects and rotational motion of the fluid and assumes the flow as an irrotational flow field. One of the most adequate methods for modelling potential fields is the boundary element method, which is employed in this article. A novel iterative scheme is used to capture the free surface of an axisymmetric supercavity. This numerical algorithm is based on updating an initial guess for the cavity's boundary; the convergence criterion is the pressure amount on the free surface of the cavity, which converges to a constant value. To obtain finite lengths for supercavities, a cavity closure model is applied. The results are in good agreement with similar analytical and numerical solutions as well as the existing experimental data for supercavities characteristic properties and the drag coefficient on cavitators. The present iterative numerical algorithm is reliable for predicting the characteristics of a supercavitating flow. Moreover, the feasibility of the cavity capturing in a flow field with low cavitation number is especially attractive.

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