The Experts below are selected from a list of 12312 Experts worldwide ranked by ideXlab platform
Damien Colombet - One of the best experts on this subject based on the ideXlab platform.
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on numerical simulation of cavitating flows under thermal regime
International Journal of Heat and Mass Transfer, 2017Co-Authors: Damien Colombet, Goncalves E Da Silva, R FortespatellaAbstract:Abstract In this work, we investigate closure laws for the description of interfacial mass transfer in cavitating flows under thermal regime. In a first part, we show that, if bubble resident time in the low pressure area of the flow is larger than the inertial/thermal regime transition time, bubble expansion are no longer monitored by Rayleigh Equation, but by heat transfer in the liquid phase at bubbles surfaces. The modelling of interfacial heat transfer depends thus on a Nusselt number that is a function of the Jakob number and of the bubble thermal Peclet number. This original approach has the advantage to include the kinetic of phase change in the description of cavitating flow and thus to link interfacial heat flux to interfacial mass flux during vapour production. The behaviour of such a model is evaluated for the case of inviscid cavitating flow in expansion tubes for water and refrigerant R114 using a four Equations mixture model. Compared with inertial regime (Rayleigh Equation), results obtained considering thermal regime seem to predict lower local gas volume fraction maxima as well as lower gradients of velocity and gas volume fraction. It is observed that global vapour production is closely monitored by volumetric interfacial area (bubble size and gas volume fraction) and mainly by the Jakob number variations. It is found that, in contrast with phase change occurring in common boiling flow, Jakob number variation is influenced by phasic temperature difference but also by density ratio variation with pressure and temperature ( Ja ∝ ( ρ L / ρ G ) Δ T ).
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On numerical simulation of cavitating flows under thermal regime
International Journal of Heat and Mass Transfer, 2017Co-Authors: Damien Colombet, Eric Goncalves Da Silva, Regiane Fortes PatellaAbstract:In this work, we investigate closure laws for the description of interfacial mass transfer in cavitating flows under thermal regime. In a first part, we show that, if bubble resident time in the low pressure area of the flow is larger than the inertial/thermal regime transition time, bubble expansion are no longer monitored by Rayleigh Equation, but by heat transfer in the liquid phase at bubbles surfaces. The modelling of inter- facial heat transfer depends thus on a Nusselt number that is a function of the Jakob number and of the bubble thermal Péclet number. This original approach has the advantage to include the kinetic of phase change in the description of cavitating flow and thus to link interfacial heat flux to interfacial mass flux during vapour production. The behaviour of such a model is evaluated for the case of inviscid cavitating flow in expansion tubes for water and refrigerant R114 using a four Equations mixture model. Compared with inertial regime (Rayleigh Equation), results obtained considering thermal regime seem to predict lower local gas volume fraction maxima as well as lower gradients of velocity and gas volume fraction. It is observed that global vapour production is closely monitored by volumetric interfacial area (bubble size and gas volume fraction) and mainly by the Jakob number variations. It is found that, in contrast with phase change occurring in common boiling flow, Jakob number variation is influenced by phasic temper- ature difference but also by density ratio variation with pressure and temperature.
Li Zou - One of the best experts on this subject based on the ideXlab platform.
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Semi-Numerical, Semi-Analytical Approximations of the Rayleigh Equation for Gas-Filled Hyper-Spherical Bubble
International Journal of Computational Methods, 2018Co-Authors: Yupeng Qin, Zhen Wang, Li ZouAbstract:A new semi-numerical, semi-analytical approach based on the differential transform method is proposed to solve the problems of a gas-filled hyper-spherical bubble governed by the Rayleigh Equation. Semi-numerical, semi-analytical approximations are constructed for the Rayleigh Equation in the form of piecewise functions. The proposed approach is compared with the standard fourth-order Runge–Kutta method and the standard differential transform method, respectively. The results reveal two main benefits of the new approach, one is that it possesses result with higher precision than the standard fourth-order Runge–Kutta method, the other is that it remains valid and accurate for longer time compared to the standard differential transform method. In addition, we also consider the Rayleigh Equation in [Formula: see text] dimensions when the surface tension is not zero.
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Semi-Numerical, Semi-Analytical Approximations of the Rayleigh Equation for Gas-Filled Hyper-Spherical Bubble
International Journal of Computational Methods, 2018Co-Authors: Yupeng Qin, Zhen Wang, Li ZouAbstract:A new semi-numerical, semi-analytical approach based on the differential transform method is proposed to solve the problems of a gas-filled hyper-spherical bubble governed by the Rayleigh Equation....
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Parametric analytical solution for the N-dimensional Rayleigh Equation
Applied Mathematics Letters, 2018Co-Authors: Yupeng Qin, Zhen Wang, Li ZouAbstract:Abstract In this letter, we consider the N -dimensional Rayleigh Equation for describing the dynamics of gas-filled spherical bubbles. In the spirit of Kudryashov and Sinelshchikov’s work in Refs. Kudryashov and Sinelshchikov (2014), (2015), (2016), a direct approach is first proposed to construct parametric analytical solution for this Equation using trigonometric function. It provides us a simple but efficient way to construct analytical solutions of the bubble radius and period. As its applications, isothermal and adiabatic compressions are studied respectively. We show that both bubble radius and period decrease with the increase in the pressure ratio.
Gen-qiang Wang - One of the best experts on this subject based on the ideXlab platform.
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Existence of Periodic Solutions for Second Order Rayleigh Equations With Piecewise Constant Argument
Turkish Journal of Mathematics, 2006Co-Authors: Gen-qiang WangAbstract:Based on a continuation theorem of Mawhin, periodic solutions are found for the second-order Rayleigh Equation with piecewise constant argument.
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A priori bounds for periodic solutions of a delay Rayleigh Equation with damping
Tamkang Journal of Mathematics, 2003Co-Authors: Gen-qiang Wang, Sui Sun ChengAbstract:A priori bounds are established for periodic solutions of a Rayleigh Equation with delay and damping. Such bounds are useful since existence theorems for periodic solutions can then be obtained by means of Mawhin's continuation theorem.
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On existence of periodic solutions of the Rayleigh Equation of retarded type
International Journal of Mathematics and Mathematical Sciences, 2000Co-Authors: Gen-qiang Wang, Jurang YanAbstract:In this paper, we give two sufficient conditions on the existence of periodic solutions of the non-autonomous Rayleigh Equation of retarded type by using the coincidence degree theory.
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EXISTENCE THEOREM OF PERIODIC POSITIVE SOLUTIONS FOR THE Rayleigh Equation OF RETARDED TYPE
Portugaliae Mathematica, 2000Co-Authors: Gen-qiang Wang, Jurang YanAbstract:In this paper, by using the coincidence degree theory, we give four su-cient conditions on the existence of periodic positive solutions of the following non- autonomous Rayleigh Equation of retarded type x 00 + f(t;x 0 (tiae))+ g(t;x(ti?)) = p(t) :
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A PRIORI BOUNDS FOR PERIODIC SOLUTIONS OF A DELAY Rayleigh Equation
Applied Mathematics Letters, 1999Co-Authors: Gen-qiang Wang, Sui Sun ChengAbstract:Abstract A priori bounds are established for periodic solutions of a Rayleigh Equation with delay. By means of these bounds, an existence theorem for periodic solutions can be obtained by means of Mawhin's continuation theorem.
Regiane Fortes Patella - One of the best experts on this subject based on the ideXlab platform.
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On numerical simulation of cavitating flows under thermal regime
International Journal of Heat and Mass Transfer, 2017Co-Authors: Damien Colombet, Eric Goncalves Da Silva, Regiane Fortes PatellaAbstract:In this work, we investigate closure laws for the description of interfacial mass transfer in cavitating flows under thermal regime. In a first part, we show that, if bubble resident time in the low pressure area of the flow is larger than the inertial/thermal regime transition time, bubble expansion are no longer monitored by Rayleigh Equation, but by heat transfer in the liquid phase at bubbles surfaces. The modelling of inter- facial heat transfer depends thus on a Nusselt number that is a function of the Jakob number and of the bubble thermal Péclet number. This original approach has the advantage to include the kinetic of phase change in the description of cavitating flow and thus to link interfacial heat flux to interfacial mass flux during vapour production. The behaviour of such a model is evaluated for the case of inviscid cavitating flow in expansion tubes for water and refrigerant R114 using a four Equations mixture model. Compared with inertial regime (Rayleigh Equation), results obtained considering thermal regime seem to predict lower local gas volume fraction maxima as well as lower gradients of velocity and gas volume fraction. It is observed that global vapour production is closely monitored by volumetric interfacial area (bubble size and gas volume fraction) and mainly by the Jakob number variations. It is found that, in contrast with phase change occurring in common boiling flow, Jakob number variation is influenced by phasic temper- ature difference but also by density ratio variation with pressure and temperature.
R Fortespatella - One of the best experts on this subject based on the ideXlab platform.
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on numerical simulation of cavitating flows under thermal regime
International Journal of Heat and Mass Transfer, 2017Co-Authors: Damien Colombet, Goncalves E Da Silva, R FortespatellaAbstract:Abstract In this work, we investigate closure laws for the description of interfacial mass transfer in cavitating flows under thermal regime. In a first part, we show that, if bubble resident time in the low pressure area of the flow is larger than the inertial/thermal regime transition time, bubble expansion are no longer monitored by Rayleigh Equation, but by heat transfer in the liquid phase at bubbles surfaces. The modelling of interfacial heat transfer depends thus on a Nusselt number that is a function of the Jakob number and of the bubble thermal Peclet number. This original approach has the advantage to include the kinetic of phase change in the description of cavitating flow and thus to link interfacial heat flux to interfacial mass flux during vapour production. The behaviour of such a model is evaluated for the case of inviscid cavitating flow in expansion tubes for water and refrigerant R114 using a four Equations mixture model. Compared with inertial regime (Rayleigh Equation), results obtained considering thermal regime seem to predict lower local gas volume fraction maxima as well as lower gradients of velocity and gas volume fraction. It is observed that global vapour production is closely monitored by volumetric interfacial area (bubble size and gas volume fraction) and mainly by the Jakob number variations. It is found that, in contrast with phase change occurring in common boiling flow, Jakob number variation is influenced by phasic temperature difference but also by density ratio variation with pressure and temperature ( Ja ∝ ( ρ L / ρ G ) Δ T ).
