The Experts below are selected from a list of 1062 Experts worldwide ranked by ideXlab platform
Guenter Ahlers - One of the best experts on this subject based on the ideXlab platform.
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reynolds numbers and the elliptic approximation near the ultimate state of turbulent rayleigh benard convection
New Journal of Physics, 2015Co-Authors: Xiaozhou He, Dennis P M Van Gils, Eberhard Bodenschatz, Guenter AhlersAbstract:We report results of Reynolds-number measurements, based on multi-point temperature measurements and the elliptic approximation (EA) of He and Zhang (2006 Phys. Rev. E 73 055303), Zhao and He (2009 Phys. Rev. E 79 046316) for turbulent Rayleigh–Benard convection (RBC) over the Rayleigh-number range and for a Prandtl number Pr 0.8. The sample was a Right-Circular Cylinder with the diameter D and the height L both equal to 112 cm. The Reynolds numbers ReU and ReV were obtained from the mean-flow velocity U and the root-mean-square fluctuation velocity V, respectively. Both were measured approximately at the mid-height of the sample and near (but not too near) the side wall close to a maximum of ReU. A detailed examination, based on several experimental tests, of the applicability of the EA to turbulent RBC in our parameter range is provided. The main contribution to ReU came from a large-scale circulation in the form of a single convection roll with the preferred azimuthal orientation of its down flow nearly coinciding with the location of the measurement probes. First we measured time sequences of ReU(t) and ReV(t) from short (10 s) segments which moved along much longer sequences of many hours. The corresponding probability distributions of ReU(t) and ReV(t) had single peaks and thus did not reveal significant flow reversals. The two averaged Reynolds numbers determined from the entire data sequences were of comparable size. For both ReU and ReV could be described by a power-law dependence on Ra with an exponent ζ close to 0.44. This exponent is consistent with several other measurements for the classical RBC state at smaller Ra and larger Pr and with the Grossmann–Lohse (GL) prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse 2001 86 3316; Grossmann and Lohse 2002 66 016305) but disagrees with the prediction by GL (Grossmann and Lohse 2004 Phys. Fluids 16 4462) for ReV. At the dependence of ReV on Ra changed, and for larger Ra , consistent with the prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse Phys. Rev. Lett. 2001 86 3316; Grossmann and Lohse Phys. Rev. E 2002 66 016305; Grossmann and Lohse 2012 Phys. Fluids 24 125103) in the ultimate state of RBC.
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reynolds numbers and the elliptic approximation near the ultimate state of turbulent rayleigh benard convection
New Journal of Physics, 2015Co-Authors: Xiaozhou He, Dennis P M Van Gils, Eberhard Bodenschatz, Guenter AhlersAbstract:We report results of Reynolds-number measurements, based on multi-point temperature measurements and the elliptic approximation (EA) of He and Zhang (2006 Phys. Rev. E 73 055303), Zhao and He (2009 Phys. Rev. E 79 046316) for turbulent Rayleigh–Benard convection (RBC) over the Rayleigh-number range and for a Prandtl number Pr 0.8. The sample was a Right-Circular Cylinder with the diameter D and the height L both equal to 112 cm. The Reynolds numbers ReU and ReV were obtained from the mean-flow velocity U and the root-mean-square fluctuation velocity V, respectively. Both were measured approximately at the mid-height of the sample and near (but not too near) the side wall close to a maximum of ReU. A detailed examination, based on several experimental tests, of the applicability of the EA to turbulent RBC in our parameter range is provided. The main contribution to ReU came from a large-scale circulation in the form of a single convection roll with the preferred azimuthal orientation of its down flow nearly coinciding with the location of the measurement probes. First we measured time sequences of ReU(t) and ReV(t) from short (10 s) segments which moved along much longer sequences of many hours. The corresponding probability distributions of ReU(t) and ReV(t) had single peaks and thus did not reveal significant flow reversals. The two averaged Reynolds numbers determined from the entire data sequences were of comparable size. For both ReU and ReV could be described by a power-law dependence on Ra with an exponent ζ close to 0.44. This exponent is consistent with several other measurements for the classical RBC state at smaller Ra and larger Pr and with the Grossmann–Lohse (GL) prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse 2001 86 3316; Grossmann and Lohse 2002 66 016305) but disagrees with the prediction by GL (Grossmann and Lohse 2004 Phys. Fluids 16 4462) for ReV. At the dependence of ReV on Ra changed, and for larger Ra , consistent with the prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse Phys. Rev. Lett. 2001 86 3316; Grossmann and Lohse Phys. Rev. E 2002 66 016305; Grossmann and Lohse 2012 Phys. Fluids 24 125103) in the ultimate state of RBC.
John W. Gillespie - One of the best experts on this subject based on the ideXlab platform.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Composite Structures, 2007Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Abstract Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch. Load–unload tests are performed to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Energies absorbed at different levels of damage are obtained from the load–unload curves. Two different support spans of 25.4 mm (1 in.) and 101.6 mm (4 in.) diameter with different layers (1, 2, 4, 6, 11, and 22 with 0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. After each test, the damaged plates are sectioned to visualize the extent of delamination and material damage. Numerical punch-shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Materials, 2005Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Two different support spans of 25.4 mm (1 in) and 101.6 mm (4 in) diameter with different layers (0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. Numerical punch shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 mm and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.CopyRight © 2005 by ASME
J R Xiao - One of the best experts on this subject based on the ideXlab platform.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Composite Structures, 2007Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Abstract Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch. Load–unload tests are performed to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Energies absorbed at different levels of damage are obtained from the load–unload curves. Two different support spans of 25.4 mm (1 in.) and 101.6 mm (4 in.) diameter with different layers (1, 2, 4, 6, 11, and 22 with 0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. After each test, the damaged plates are sectioned to visualize the extent of delamination and material damage. Numerical punch-shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Materials, 2005Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Two different support spans of 25.4 mm (1 in) and 101.6 mm (4 in) diameter with different layers (0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. Numerical punch shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 mm and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.CopyRight © 2005 by ASME
Bazle A Gama - One of the best experts on this subject based on the ideXlab platform.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Composite Structures, 2007Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Abstract Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch. Load–unload tests are performed to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Energies absorbed at different levels of damage are obtained from the load–unload curves. Two different support spans of 25.4 mm (1 in.) and 101.6 mm (4 in.) diameter with different layers (1, 2, 4, 6, 11, and 22 with 0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. After each test, the damaged plates are sectioned to visualize the extent of delamination and material damage. Numerical punch-shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.
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progressive damage and delamination in plain weave s 2 glass sc 15 composites under quasi static punch shear loading
Materials, 2005Co-Authors: J R Xiao, Bazle A Gama, John W. GillespieAbstract:Quasi-static punch-shear tests are carried out on plain weave (PW) S-2 glass/SC-15 epoxy composite laminates with a Right Circular Cylinder punch to identify the sequence and extent of damage and the corresponding displacements at which they occur for a wide range of laminate thicknesses. Two different support spans of 25.4 mm (1 in) and 101.6 mm (4 in) diameter with different layers (0.6 mm ply thickness) of composite laminates are tested under quasi-static loading to identify compression-shear and tension-shear dominated modes of damage. Numerical punch shear experiments are conducted using LS-DYNA 970. The numerical modeling is carried out using a newly developed composite damage model, namely MAT 162, which has been incorporated into LS-DYNA. MAT 162 uses damage mechanics principle for progressive damage and material degradation. Input data required in MAT 162 have been calibrated to match the experimental results of 22-layer composite plate of both spans (25.4 mm and 101.6 mm). The calibrated material properties have been used to simulate other thicknesses, and the simulated results show good agreement with experiment results. It has been found that the dominant damage mechanisms are delamination and fiber breakage due to shear and tension.CopyRight © 2005 by ASME
Xiaozhou He - One of the best experts on this subject based on the ideXlab platform.
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reynolds numbers and the elliptic approximation near the ultimate state of turbulent rayleigh benard convection
New Journal of Physics, 2015Co-Authors: Xiaozhou He, Dennis P M Van Gils, Eberhard Bodenschatz, Guenter AhlersAbstract:We report results of Reynolds-number measurements, based on multi-point temperature measurements and the elliptic approximation (EA) of He and Zhang (2006 Phys. Rev. E 73 055303), Zhao and He (2009 Phys. Rev. E 79 046316) for turbulent Rayleigh–Benard convection (RBC) over the Rayleigh-number range and for a Prandtl number Pr 0.8. The sample was a Right-Circular Cylinder with the diameter D and the height L both equal to 112 cm. The Reynolds numbers ReU and ReV were obtained from the mean-flow velocity U and the root-mean-square fluctuation velocity V, respectively. Both were measured approximately at the mid-height of the sample and near (but not too near) the side wall close to a maximum of ReU. A detailed examination, based on several experimental tests, of the applicability of the EA to turbulent RBC in our parameter range is provided. The main contribution to ReU came from a large-scale circulation in the form of a single convection roll with the preferred azimuthal orientation of its down flow nearly coinciding with the location of the measurement probes. First we measured time sequences of ReU(t) and ReV(t) from short (10 s) segments which moved along much longer sequences of many hours. The corresponding probability distributions of ReU(t) and ReV(t) had single peaks and thus did not reveal significant flow reversals. The two averaged Reynolds numbers determined from the entire data sequences were of comparable size. For both ReU and ReV could be described by a power-law dependence on Ra with an exponent ζ close to 0.44. This exponent is consistent with several other measurements for the classical RBC state at smaller Ra and larger Pr and with the Grossmann–Lohse (GL) prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse 2001 86 3316; Grossmann and Lohse 2002 66 016305) but disagrees with the prediction by GL (Grossmann and Lohse 2004 Phys. Fluids 16 4462) for ReV. At the dependence of ReV on Ra changed, and for larger Ra , consistent with the prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse Phys. Rev. Lett. 2001 86 3316; Grossmann and Lohse Phys. Rev. E 2002 66 016305; Grossmann and Lohse 2012 Phys. Fluids 24 125103) in the ultimate state of RBC.
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reynolds numbers and the elliptic approximation near the ultimate state of turbulent rayleigh benard convection
New Journal of Physics, 2015Co-Authors: Xiaozhou He, Dennis P M Van Gils, Eberhard Bodenschatz, Guenter AhlersAbstract:We report results of Reynolds-number measurements, based on multi-point temperature measurements and the elliptic approximation (EA) of He and Zhang (2006 Phys. Rev. E 73 055303), Zhao and He (2009 Phys. Rev. E 79 046316) for turbulent Rayleigh–Benard convection (RBC) over the Rayleigh-number range and for a Prandtl number Pr 0.8. The sample was a Right-Circular Cylinder with the diameter D and the height L both equal to 112 cm. The Reynolds numbers ReU and ReV were obtained from the mean-flow velocity U and the root-mean-square fluctuation velocity V, respectively. Both were measured approximately at the mid-height of the sample and near (but not too near) the side wall close to a maximum of ReU. A detailed examination, based on several experimental tests, of the applicability of the EA to turbulent RBC in our parameter range is provided. The main contribution to ReU came from a large-scale circulation in the form of a single convection roll with the preferred azimuthal orientation of its down flow nearly coinciding with the location of the measurement probes. First we measured time sequences of ReU(t) and ReV(t) from short (10 s) segments which moved along much longer sequences of many hours. The corresponding probability distributions of ReU(t) and ReV(t) had single peaks and thus did not reveal significant flow reversals. The two averaged Reynolds numbers determined from the entire data sequences were of comparable size. For both ReU and ReV could be described by a power-law dependence on Ra with an exponent ζ close to 0.44. This exponent is consistent with several other measurements for the classical RBC state at smaller Ra and larger Pr and with the Grossmann–Lohse (GL) prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse 2001 86 3316; Grossmann and Lohse 2002 66 016305) but disagrees with the prediction by GL (Grossmann and Lohse 2004 Phys. Fluids 16 4462) for ReV. At the dependence of ReV on Ra changed, and for larger Ra , consistent with the prediction for ReU (Grossmann and Lohse 2000 J. Fluid. Mech. 407 27; Grossmann and Lohse Phys. Rev. Lett. 2001 86 3316; Grossmann and Lohse Phys. Rev. E 2002 66 016305; Grossmann and Lohse 2012 Phys. Fluids 24 125103) in the ultimate state of RBC.
