On POD analysis of PIV measurements applied to mixing in a stirred vessel with a shear thinning fluid

P.O.D. technique is applied to 2D P.I.V. data in the field of hydrodynamics in a mixing tank with a Rushton turbine and a shear thinning fluid. Classical eigen-value spectrum is presented and phase portrait of P.O.D. coefficients are plotted and analyzed in terms of trailing vortices. A spectrum of dissipation rate of kinetic energy is introduced and discussed. Length scales associated to each P.O.D. modes are proposed

Reconstruction of the 3D hydrodynamics in a baffled stirred tank using Proper Orthogonal Decomposition

International audienceIn this work, the unsteady turbulent flow in a four-baffled stirred tank equipped with a Rushton turbine is computed with ANSYS FLUENT (R) using the sliding mesh technique. The POD algorithm is applied first to each mesh zone (fixed and rotating) and, in a novel and original way, to the full 3D CFD data without distinguishing between the stationary and rotating zones. The resulting modes cannot be regarded as spatial modes revealing the underlying flow structure. The POD results showed that 99.9% of the system variance is recovered with the first three modes. The reconstruction of the velocity field from these modes reveals the trailing vortices plus the mean flow. The accuracy of the POD reconstructed flow fields is quantified. The present work is the first evidence of a POD reconstruction of the unsteady turbulent flow performed over the entire 3D domain in a baffled stirred tank

Evaluation of local kinetic energy dissipation rate in the impeller stream of a Rushton turbine by time-resolved PIV

International audienceThe present paper is dedicated to the direct measurement of the dissipation rate of kinetic energy, ¯ε, by means of time-resolved 2D-PIV, in the impeller region of a stirred vessel. Experimental estimation of ¯ε is carried out without simplifications, since all spatial gradients of the fluctuating velocity components are directly measured. At each point, measurements have thus been realized in three orthogonal planes. The present results have been compared with previous ones and discussed according to experimental techniques. A special attention is focused on the contribution of measurements in each plane and some newideas have been suggested for the assessment of ¯ε. In addition, in each measurement plane, the time-variation of the instantaneous fluctuating velocity gradients have been also presented, exhibiting periodicity, with large values of instantaneous dissipation rate, linked to the trailing vortex induced by the blade rotation

13th European Conference on Mixing: New developments towards more efficient and sustainable operations

Trattasi di un fascicolo monografico della rivista Chem. Eng. Res. Des. edito in occasione della '13th European Conference on Mixing', tenutasi a Londra nel 2009

Expressão diferencial e variação alélica de genes associados à tolerância à seca em trigo.

201

Papillary endothelial hyperplasia (Masson's tumor) in children

International audienc