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Rotating Body (rotating + body)
Selected AbstractsExistence of a weak solution to the Navier,Stokes equation in a general time-varying domain by the Rothe methodMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 6 2009í Neustupa Abstract We assume that ,t is a domain in ,3, arbitrarily (but continuously) varying for 0,t,T. We impose no conditions on smoothness or shape of ,t. We prove the global in time existence of a weak solution of the Navier,Stokes equation with Dirichlet's homogeneous or inhomogeneous boundary condition in Q[0,,T) := {(x,,t);0,t,T, x,,t}. The solution satisfies the energy-type inequality and is weakly continuous in dependence of time in a certain sense. As particular examples, we consider flows around rotating bodies and around a body striking a rigid wall. Copyright © 2008 John Wiley & Sons, Ltd. [source] Suppression of vortex shedding for flow around a circular cylinder using optimal controlINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 1 2002C. Homescu Abstract Adjoint formulation is employed for the optimal control of flow around a rotating cylinder, governed by the unsteady Navier,Stokes equations. The main objective consists of suppressing Karman vortex shedding in the wake of the cylinder by controlling the angular velocity of the rotating body, which can be constant in time or time-dependent. Since the numerical control problem is ill-posed, regularization is employed. An empirical logarithmic law relating the regularization coefficient to the Reynolds number was derived for 60,Re,140. Optimal values of the angular velocity of the cylinder are obtained for Reynolds numbers ranging from Re=60 to Re=1000. The results obtained by the computational optimal control method agree with previously obtained experimental and numerical observations. A significant reduction of the amplitude of the variation of the drag coefficient is obtained for the optimized values of the rotation rate. Copyright © 2002 John Wiley & Sons, Ltd. [source] Identification of the inertia matrix of a rotating body based on errors-in-variables modelsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 3 2010Byung-Eul Jun Abstract This paper proposes a procedure for identifying the inertia matrix of a rotating body. The procedure based on Euler's equation governing rotational motion assumes errors-in-variables models in which all measurements, torque as well as angular velocities, are corrupted by noises. In order for consistent estimation, we introduce an extended linear regression model by augmenting the regressors with constants and the parameters with noise-contributed terms. A transformation, based on low-pass filtering, of the extended model cancels out angular acceleration terms in the regressors. Applying the method of least correlation to the model identifies the elements of the inertia matrix. Analysis shows that the estimates converge to the true parameters as the number of samples increases to infinity. Monte Carlo simulations demonstrate the performance of the algorithm and support the analytical consistency. Copyright © 2009 John Wiley & Sons, Ltd. [source] A weighted Lq -approach to Oseen flow around a rotating bodyMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 5 2008R. Farwig Abstract We study time-periodic Oseen flows past a rotating body in ,3 proving weighted a priori estimates in Lq -spaces using Muckenhoupt weights. After a time-dependent change of coordinates the problem is reduced to a stationary Oseen equation with the additional terms (,,,,x),,,,,u and ,,,,,u in the equation of momentum where , denotes the angular velocity. Due to the asymmetry of Oseen flow and to describe its wake we use anisotropic Muckenhoupt weights, a weighted theory of Littlewood,Paley decomposition and of maximal operators as well as one-sided univariate weights, one-sided maximal operators and a new version of Jones' factorization theorem. Copyright © 2007 John Wiley & Sons, Ltd. [source] | ||||||||||