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Alexander F Vakakis - One of the best experts on this subject based on the ideXlab platform.

  • effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$ , with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$ .

  • Effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex-induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range , with based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low .

Ravi Kumar R Tumkur - One of the best experts on this subject based on the ideXlab platform.

  • effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$ , with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$ .

  • Effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex-induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range , with based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low .

Zahra Atlasbaf - One of the best experts on this subject based on the ideXlab platform.

  • Analysis and Synthesis of Singly-Curved Microstrip Structures Utilizing Modified Schwarz-Christoffel Transformation
    IEEE Transactions on Antennas and Propagation, 2013
    Co-Authors: Keyhan Hosseini, Zahra Atlasbaf
    Abstract:

    A new conformal mapping-based method to analyze and synthesize singly-curved microstrip structures is presented. The cross-section of such structures is usually an Elongated Region with curved boundaries. Under a conventional Schwarz-Christoffel Transformation (SCT), elongation causes the undesirable crowding phenomenon. Also, the curvature is not taken into account. To circumvent crowding, SCT is modified so that it maps an Elongated straight strip into a polygon with both ends at infinity. Curvature is accounted for by fitting each segment of the curved boundaries with a second degree polynomial function of SCT prevertices. This mapping is called Modified Schwarz-Christoffel Transformation (MSCT) which proves to be a fast and accurate method to deal with electromagnetic structures. As a test case, a composite right/left-handed (CRLH) conformal leaky-wave antenna (LWA) located on an elliptic cylinder is investigated. The antenna is designed to have broadside radiation at 7.75 GHz and Bloch impedance 50 Ω around its radiation regime. Its scattering parameters and E-plane radiation patterns are calculated by MSCT and are compared with full-wave simulation and fabrication results which show good agreement.

Antoine Blanchard - One of the best experts on this subject based on the ideXlab platform.

  • effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$ , with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$ .

  • Effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex-induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range , with based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low .

Arne J Pearlstein - One of the best experts on this subject based on the ideXlab platform.

  • effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range $20\leqslant Re\leqslant 120$ , with $Re$ based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low $Re$ .

  • Effect of an internal nonlinear rotational dissipative element on vortex shedding and vortex-induced vibration of a sprung circular cylinder
    Journal of Fluid Mechanics, 2017
    Co-Authors: Ravi Kumar R Tumkur, Arne J Pearlstein, Arif Masud, O V Gendelman, Antoine Blanchard, Lawrence A Bergman, Alexander F Vakakis
    Abstract:

    We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range , with based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly Elongated Region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low .