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Author: Christopher R. Morton Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flow past circular cylinders with stepwise discontinuities in diameter was investigated experimentally and numerically for the diameter ratio D/d = 2 and three Reynolds numbers, Re = 150, 300, and 1050. The investigation was focused on the vortex shedding phenomena occurring in the wake of the cylinders. In the first series of experimental and numerical studies, the flow development past a single step cylinder was investigated. The single step cylinder model is comprised of a small diameter cylinder (d) attached coaxially to a large diameter cylinder (D). The results show that three distinct spanwise vortex cells form in the step cylinder wake: a single vortex shedding cell in the wake of the small cylinder (the S-cell) and two vortex shedding cells in the wake of the large cylinder, one in the region downstream of the step (the N-cell) and the other away from the step (the L-cell). Due to the differences in vortex shedding frequencies between the three cells, complex vortex connections occur in two vortex-interaction regions located between the adjacent cells. The region at the boundary between the S-cell and the N-cell is relatively narrow and its spanwise extent does not fluctuate significantly. In this region, vortex dislocations manifested as half-loop connections between two S-cell vortices of opposite sign. In contrast, the region at the boundary between the N-cell and the L-cell exhibits a transient behavior, with large scale vortex dislocations causing cyclic variation in the extent of N-cell vortices. For Re = 300 and 1050, small scale streamwise vortices forming in the wake complicate the vortex dynamics within the adjacent S-cell and L-cell. There is no significant Reynolds number effect on the average spanwise extent of the vortex cells and the two transition regions between neighboring cells. Finally, formation of N-cell vortices is linked to downwash fluctuations near the step. The flow development past a dual step cylinder was studied experimentally for Re = 1050. The dual step cylinder model is comprised of a small diameter cylinder (d) and a large diameter cylinder (D) mounted at the mid-span of the small cylinder. The experiments were completed for a range of large cylinder aspect ratios 0.2 ≤ L/D ≤ 17. The flow development is highly dependent on the aspect ratio of the large cylinder, L/D. The results identify four distinct flow regimes: (i) for L/D = 17, three vortex shedding cells form in the wake of the large cylinder, one central cell and two cells of lower frequency extending over about 4.5D from the large cylinder ends, (ii) for 7
Author: Christopher R. Morton Publisher: ISBN: Category : Languages : en Pages :
Book Description
Flow past circular cylinders with stepwise discontinuities in diameter was investigated experimentally and numerically for the diameter ratio D/d = 2 and three Reynolds numbers, Re = 150, 300, and 1050. The investigation was focused on the vortex shedding phenomena occurring in the wake of the cylinders. In the first series of experimental and numerical studies, the flow development past a single step cylinder was investigated. The single step cylinder model is comprised of a small diameter cylinder (d) attached coaxially to a large diameter cylinder (D). The results show that three distinct spanwise vortex cells form in the step cylinder wake: a single vortex shedding cell in the wake of the small cylinder (the S-cell) and two vortex shedding cells in the wake of the large cylinder, one in the region downstream of the step (the N-cell) and the other away from the step (the L-cell). Due to the differences in vortex shedding frequencies between the three cells, complex vortex connections occur in two vortex-interaction regions located between the adjacent cells. The region at the boundary between the S-cell and the N-cell is relatively narrow and its spanwise extent does not fluctuate significantly. In this region, vortex dislocations manifested as half-loop connections between two S-cell vortices of opposite sign. In contrast, the region at the boundary between the N-cell and the L-cell exhibits a transient behavior, with large scale vortex dislocations causing cyclic variation in the extent of N-cell vortices. For Re = 300 and 1050, small scale streamwise vortices forming in the wake complicate the vortex dynamics within the adjacent S-cell and L-cell. There is no significant Reynolds number effect on the average spanwise extent of the vortex cells and the two transition regions between neighboring cells. Finally, formation of N-cell vortices is linked to downwash fluctuations near the step. The flow development past a dual step cylinder was studied experimentally for Re = 1050. The dual step cylinder model is comprised of a small diameter cylinder (d) and a large diameter cylinder (D) mounted at the mid-span of the small cylinder. The experiments were completed for a range of large cylinder aspect ratios 0.2 ≤ L/D ≤ 17. The flow development is highly dependent on the aspect ratio of the large cylinder, L/D. The results identify four distinct flow regimes: (i) for L/D = 17, three vortex shedding cells form in the wake of the large cylinder, one central cell and two cells of lower frequency extending over about 4.5D from the large cylinder ends, (ii) for 7
Author: Christopher R. Morton Publisher: ISBN: Category : Languages : en Pages : 123
Book Description
Flow past circular cylinders with stepwise discontinuities in diameter was investigated experimentally and numerically for the diameter ratio D/d = 2 and three Reynolds numbers, Re = 150, 300, and 1050. The investigation was focused on the vortex shedding phenomena occurring in the wake of the cylinders. In the first series of experimental and numerical studies, the flow development past a single step cylinder was investigated. The single step cylinder model is comprised of a small diameter cylinder (d) attached coaxially to a large diameter cylinder (D). The results show that three distinct spanwise vortex cells form in the step cylinder wake: a single vortex shedding cell in the wake of the small cylinder (the S-cell) and two vortex shedding cells in the wake of the large cylinder, one in the region downstream of the step (the N-cell) and the other away from the step (the L-cell). Due to the differences in vortex shedding frequencies between the three cells, complex vortex connections occur in two vortex-interaction regions located between the adjacent cells. The region at the boundary between the S-cell and the N-cell is relatively narrow and its spanwise extent does not fluctuate significantly. In this region, vortex dislocations manifested as half-loop connections between two S-cell vortices of opposite sign. In contrast, the region at the boundary between the N-cell and the L-cell exhibits a transient behavior, with large scale vortex dislocations causing cyclic variation in the extent of N-cell vortices. For Re = 300 and 1050, small scale streamwise vortices forming in the wake complicate the vortex dynamics within the adjacent S-cell and L-cell. There is no significant Reynolds number effect on the average spanwise extent of the vortex cells and the two transition regions between neighboring cells. Finally, formation of N-cell vortices is linked to downwash fluctuations near the step. The flow development past a dual step cylinder was studied experimentally for Re = 1050. The dual step cylinder model is comprised of a small diameter cylinder (d) and a large diameter cylinder (D) mounted at the mid-span of the small cylinder. The experiments were completed for a range of large cylinder aspect ratios 0.2 [les] L/D [les] 17. The flow development is highly dependent on the aspect ratio of the large cylinder, L/D. The results identify four distinct flow regimes: (i) for L/D = 17, three vortex shedding cells form in the wake of the large cylinder, one central cell and two cells of lower frequency extending over about 4.5D from the large cylinder ends, (ii) for 7
Author: K. Murali Publisher: Springer ISBN: 9811331197 Category : Technology & Engineering Languages : en Pages : 1048
Book Description
This book comprises selected proceedings of the Fourth International Conference in Ocean Engineering (ICOE2018), focusing on emerging opportunities and challenges in the field of ocean engineering and offshore structures. It includes state-of-the-art content from leading international experts, making it a valuable resource for researchers and practicing engineers alike.
Author: Assma Begum Publisher: ISBN: 9780438148291 Category : Cylinders Languages : en Pages : 57
Book Description
Abstract: Numerical investigations of flow past rotating circular cylinders with and without wires wrapped on the surface of the cylinder were studied using Computational Fluid Dynamics (CFD). The flow characteristics such as flow separation, shedding of the primary and secondary vortices, and drag coefficients were investigated. The software STAR CCM+ from Siemens PLM was used in all investigations. Three-dimensional Unsteady Reynolds Average Navier Stokes (URANS) equations were utilized. The free stream mean velocity was constant at 10 m/sec, which corresponded to an approximate Reynolds number based on cylinder’s diameter of 32,000. The results are presented for cylinders with and without wires at varying rotation rates [alpha] of 0, 0.5, and 1. This is represented by [alpha], the ratio of the tangential velocity at the cylinder to that of the free stream velocity of the flow. As the rotation rate increased from 0 to 1, the drag coefficient for the smooth rotating cylinder reduced, while the drag coefficient for the wire-wrapped cylinder increased. The wire-wrapped cylinder produced significantly higher lift when compared with the corresponding value for the smooth cylinder. Increasing the rotation rate increases the lift and lift to drag ratio.
Author: M.M. Zdravkovich Publisher: Oxford University Press ISBN: 9780198565611 Category : Mathematics Languages : en Pages : 628
Book Description
This text offers an authoritative compilation of experimental data, theoretical models, and computer simulations which will provide the reader with a comprehensive survey of research work on the phenomenon of flow around circular cylinders.
Author: G. Urriolagoitia-Calderón Publisher: Trans Tech Publications Ltd ISBN: 3038132969 Category : Technology & Engineering Languages : en Pages : 160
Book Description
Volume is indexed by Thomson Reuters CPCI-S (WoS). This volume presents selected peer-reviewed papers related to diverse aspects of mechanics and materials. Cases related to the flow of fluids under various conditions, as well as heat transfer, are analyzed. There are also contributions, to the field of the design of mechanisms, which focus on biomechanics and the synthesis of mechanisms. Papers on mechanical vibration are linked to the design of machine tools, rotodynamics and vibrations in microbeams. Also, the evaluation of residual stresses and the estimation of the mechanical properties of vegetal materials are treated. Finally, fractal analysis is applied to solar radiation, and to the materials used in nanomedicine.
Author: Hyun Jin Kim Publisher: ISBN: Category : Aerospace engineering Languages : en Pages : 506
Book Description
An experimental investigation has been carried out on the flow transitions around a smooth circular cylinder in the initial stage of the critical Reynolds number region, where drag coefficient starts to decrease. In this Reynolds number region, intermitent reattachment of the separated boundary layer was found, while only initial separation position excursion was observed in the subcritical region. Large spanwise variations in the surface pressure and wake velocity observed in the first critical subregion were associated with local wake width pulsations caused by spanwise phase variations in the unsteady flow reattachment.
Author: Christopher R. Morton
Author: Christopher R. Morton
Author: Christopher R. Morton
Author: Bjørn H. Hjertager
Author: K. Murali
Author: Assma Begum
Author: M.M. Zdravkovich
Author: G. Urriolagoitia-Calderón
Author: Hyun Jin Kim
Author: Byram Bays-Muchmore
Author: M. Budair