The Experts below are selected from a list of 267 Experts worldwide ranked by ideXlab platform
Baoji Zhang - One of the best experts on this subject based on the ideXlab platform.
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Study on Mooring Design and Calculation Method of Ocean Farm Based on Time-Domain Potential Flow Theory
Journal of Marine Science, 2020Co-Authors: Baoji Zhang, Yuhang SunAbstract:In order to calculate the mooring force of a new semi-submerged Ocean Farm quickly and accurately, based on the unsteady time-domain Potential Flow Theory and combined the catenary model, the control equation of mooring cable is established, and the mooring force of the platform under the wave spectrum is calculated. First of all, based on the actual situation of the ocean environment and platform, the mooring design of the platform is carried out, and the failure analysis and sensitivity analysis of the single anchor chain by the time domain coupling method are adopted: including different water depth, cycle, pretension size, anchor chain layout direction and wind speed, etc. The analysis results confirm the reliability of anchoring method. Based on this, the mooring point location of the platform is determined, the force of each anchor chain in the anchoring process is calculated, and the mooring force and the number of mooring cables are obtained for each cable that satisfies the specification, the results of this paper can provide theoretical calculation methods for mooring setting and mooring force calculation of similar offshore platforms.
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the research of added resistance in waves based on nonlinear time domain Potential Flow Theory
Journal of Marine Science and Technology, 2018Co-Authors: Baoji ZhangAbstract:In order to accurately predict the motion performance of the ship in waves, the numerical calculation of heave, pitch and added resistance of a container ship in a regular wave is studied based on the three-dimensional fully nonlinear time-domain Potential Flow Theory. The boundary element method is used to deal with the quadrilateral elements, and the governing equations are solved by the first-order flat-plate Theory and the fourth-order Runge- Kutta time integration method. The ship hull is divided by the fixed mesh. Considering the non-linear superposition of the forward velocity, the stationary ship wave, diffracted wave, diffraction wave and incident wave field, the free surface is generated by the hybrid Euler-Lagrangian method, and the damping area is set manually at the edge. Take the KCS container ship for instance, the calculation results of heave, pitch and added resistance in waves are compared with the experimental values. The results show that the biggest advantage of this method is to get a more accurate prediction of ship motion in a short time, and this method has a broad application prospect in the analysis and motion prediction of ship hydrodynamic performance in waves.
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The Optimization of the Hull Form with the Minimum Wave-Making Resistance Based on Potential Flow Theory
Research on Ship Design and Optimization Based on Simulation-Based Design (SBD) Technique, 2018Co-Authors: Baoji Zhang, Sheng-long ZhangAbstract:Based on the Michell integral method and the Rankine source method, the parameters of the double-triangle ship modification function are used as the design variables. Under the condition of ensuring the drainage volume as the basic constraint, the optimal design model of nonlinear programming method (NLP), traditional genetic algorithm (SGA), and niche genetic algorithm (NGA) are established by considering the influence of tail-viscosity separation. The whole ship linear optimization design program with independent intellectual property rights is developed, and the effectiveness of the program is verified through experiments. The research results have important guiding significance to promote the ship design from the traditional experience mode to the knowledge-based mode.
Marcel Ilie - One of the best experts on this subject based on the ideXlab platform.
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numerical study of helicopter blade vortex mechanism of interaction using the Potential Flow Theory
Applied Mathematical Modelling, 2012Co-Authors: Patricia X. Coronado Domenge, Marcel IlieAbstract:Abstract The blade–vortex interaction (BVI) phenomenon plays a key role in the rotorcraft aerodynamics. Numerical investigations of BVI using classical CFD approaches are computationally expensive. In the present research we propose a numerical approach, based on the Potential Flow Theory, for the numerical investigation of helicopter blade–vortex mechanism of interaction. This approach overcomes the computational expenses posed by the CFD techniques. The influence of vertical miss distance, angle of attack, airfoil camber, and vortex strength on the helicopter blade–vortex mechanism of interaction is subject of investigation. The study reveals that the magnitude of the aerodynamic coefficients decreases with the increase of vertical miss distance and angle of attack, and the decrease of vortex strength and core size.
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Numerical study of helicopter blade–vortex mechanism of interaction using the Potential Flow Theory
Applied Mathematical Modelling, 2012Co-Authors: Patricia X. Coronado Domenge, Marcel IlieAbstract:Abstract The blade–vortex interaction (BVI) phenomenon plays a key role in the rotorcraft aerodynamics. Numerical investigations of BVI using classical CFD approaches are computationally expensive. In the present research we propose a numerical approach, based on the Potential Flow Theory, for the numerical investigation of helicopter blade–vortex mechanism of interaction. This approach overcomes the computational expenses posed by the CFD techniques. The influence of vertical miss distance, angle of attack, airfoil camber, and vortex strength on the helicopter blade–vortex mechanism of interaction is subject of investigation. The study reveals that the magnitude of the aerodynamic coefficients decreases with the increase of vertical miss distance and angle of attack, and the decrease of vortex strength and core size.
Mukesh Kumar Awasthi - One of the best experts on this subject based on the ideXlab platform.
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Study on Electrohydrodynamic Capillary Instability with Heat and Mass Transfer
World Academy of Science Engineering and Technology International Journal of Mathematical Computational Physical Electrical and Computer Engineering, 2013Co-Authors: D. K. Tiwari, Mukesh Kumar Awasthi, G.s. AgrawalAbstract:The effect of an axial electric field on the capillary instability of a cylindrical interface in the presence of heat and mass transfer has been investigated using viscous Potential Flow Theory. In viscous Potential Flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in the viscous Potential Flow Theory and tangential stresses are not considered. A dispersion relation that accounts for the growth of axisymmetric waves is derived and stability is discussed theoretically as well as numerically. Stability criterion is given by critical value of applied electric field as well as critical wave number. Various graphs have been drawn to show the effect of various physical parameters such as electric field, heat transfer capillary number, conductivity ratio, permittivity ratio on the stability of the system. It has been observed that the axial electric field and heat and mass transfer both have stabilizing effect on the stability of the system. Keywords—Capillary instability, Viscous Potential Flow, Heat and mass transfer, Axial electric field.
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Study on hydro-magnetic capillary instability with mass transfer through porous media
International Journal of Dynamics and Control, 2013Co-Authors: Mukesh Kumar AwasthiAbstract:The linear analysis of hydro-magnetic capillary instability of a cylindrical interface between two viscous and magnetic fluids in a fully saturated porous medium has been carried out, when the fluids are subjected to a constant axial magnetic field and, when there is heat and mass transfer across the interface. The viscous Potential Flow Theory has been used for the investigation. Viscosity enters through normal stress balance in the viscous Potential Flow Theory and tangential stresses are not considered. A dispersion relation that accounts for the growth of axisymmetric waves is derived and stability is discussed theoretically as well as numerically. Stability criterion is given by critical value of applied magnetic field as well as critical wave number. Various graphs have been drawn to show the effect of various physical parameters such as magnetic field strength, heat transfer capillary number, vapour fraction, permeability and porosity on the stability of the system. It has been observed that heat transfer and magnetic field both have stabilizing effect while porosity has destabilizing effect on the stability of the system.
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Viscous Potential Flow analysis of capillary instability with radial electric field
International Journal of Theoretical and Applied Multiscale Mechanics, 2012Co-Authors: Mukesh Kumar Awasthi, G.s. AgrawalAbstract:A linear analysis of capillary instability with radial electric field is carried out using viscous Potential Flow Theory. In viscous Potential Flow, the viscous term in the Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in viscous Potential Flow Theory and the tangential stresses are not considered. The effect of gravity and free surface charges at the interface are neglected. A dispersion relation is derived for the case of radially imposed electric field and stability is discussed in terms of various parameters such as Ohnesorge number, permittivity ratio, etc. A condition for neutral stability is obtained and it is given in terms of critical value of electric field. It is observed that the radial electric field has dual effect on the stability of the system corresponding to the values of conductivities and permittivities of the fluids.
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Viscous Potential Flow analysis of Kelvin-Helmholtz instability of cylindrical interface
International Journal of Applied Mathematics and Computation, 2011Co-Authors: Mukesh Kumar Awasthi, G S AgrwalAbstract:A linear analysis of Kelvin-Helmholtz instability of cylindrical interface is carried out using viscous Potential Flow Theory. In the inviscid Potential Flow Theory, the viscous term in Navier-Stokes equation vanishes as viscosity is zero. In viscous Potential Flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in viscous Potential Flow Theory and tangential stresses are not considered. Both asymmetric and axisymmetric disturbances are considered. A dispersion relation has been obtained and stability criteria are given in the terms of the relative velocity. A comparison between inviscid Potential Flow and viscous Potential Flow has been made. It has been observed that Reynolds number and inner fluid fraction both have destabilizing effect on the stability of the system.
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Viscous Potential Flow Analysis of Rayleigh-Taylor Instability of Cylindrical Interface
Applied Mechanics and Materials, 2011Co-Authors: Rishi Asthana, Mukesh Kumar Awasthi, G.s. AgrawalAbstract:The present paper deals with the study of Rayleigh-Taylor instability at the cylindrical interface using viscous Potential Flow Theory. In the inviscid Potential Flow Theory, the viscous term in Navier-Stokes equation vanishes as viscosity is zero. In viscous Potential Flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in viscous Potential Flow Theory and tangential stresses are not considered. A dispersion relation is derived and stability is discussed in terms of various parameters such as Ohnesorge number, density ratio etc. A condition for neutral stability is obtained and it is given in terms of critical value of the wave number. It is observed that the Ohnesorge number has destabilizing effect while inner fluid fraction has stabilizing effect on the stability of the system.
Mats Leijon - One of the best experts on this subject based on the ideXlab platform.
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a time dependent Potential Flow Theory for the aerodynamics of vertical axis wind turbines
Journal of Applied Physics, 2005Co-Authors: Olov Agren, Marcus Berg, Mats LeijonAbstract:The Betz factor, i.e., the value 16∕27 for the power coefficient, is widely expected to give an upper limit for the performance of any wind turbine. In the present study, an analytical model of a vertical-axis wind turbine with straight vertical wings is developed. A goal of the work is to study if the one-dimensional Betz Theory gives an upper limit of the performance of wind turbines when two-dimensional effects are included. The two-dimensional and time-dependent Potential Flow is solved by a conformal map of the wing sections to circles. The stagnation points are determined by the Kutta condition. The calculated power coefficient exceeds the Betz limit by a large factor. This is due to a completely different Flow pattern compared to the one-dimensional Betz Theory. In aerodynamic Potential Flow, the expanding flux tube of Betz is replaced by an asymptotic Flow consisting of a superposition of homogeneous Flow and a circulation around the wings. Moreover, the total torque on a turbine with three or mor...
G.s. Agrawal - One of the best experts on this subject based on the ideXlab platform.
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Study on Electrohydrodynamic Capillary Instability with Heat and Mass Transfer
World Academy of Science Engineering and Technology International Journal of Mathematical Computational Physical Electrical and Computer Engineering, 2013Co-Authors: D. K. Tiwari, Mukesh Kumar Awasthi, G.s. AgrawalAbstract:The effect of an axial electric field on the capillary instability of a cylindrical interface in the presence of heat and mass transfer has been investigated using viscous Potential Flow Theory. In viscous Potential Flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in the viscous Potential Flow Theory and tangential stresses are not considered. A dispersion relation that accounts for the growth of axisymmetric waves is derived and stability is discussed theoretically as well as numerically. Stability criterion is given by critical value of applied electric field as well as critical wave number. Various graphs have been drawn to show the effect of various physical parameters such as electric field, heat transfer capillary number, conductivity ratio, permittivity ratio on the stability of the system. It has been observed that the axial electric field and heat and mass transfer both have stabilizing effect on the stability of the system. Keywords—Capillary instability, Viscous Potential Flow, Heat and mass transfer, Axial electric field.
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Viscous Potential Flow analysis of capillary instability with radial electric field
International Journal of Theoretical and Applied Multiscale Mechanics, 2012Co-Authors: Mukesh Kumar Awasthi, G.s. AgrawalAbstract:A linear analysis of capillary instability with radial electric field is carried out using viscous Potential Flow Theory. In viscous Potential Flow, the viscous term in the Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in viscous Potential Flow Theory and the tangential stresses are not considered. The effect of gravity and free surface charges at the interface are neglected. A dispersion relation is derived for the case of radially imposed electric field and stability is discussed in terms of various parameters such as Ohnesorge number, permittivity ratio, etc. A condition for neutral stability is obtained and it is given in terms of critical value of electric field. It is observed that the radial electric field has dual effect on the stability of the system corresponding to the values of conductivities and permittivities of the fluids.
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Viscous Potential Flow Analysis of Rayleigh-Taylor Instability of Cylindrical Interface
Applied Mechanics and Materials, 2011Co-Authors: Rishi Asthana, Mukesh Kumar Awasthi, G.s. AgrawalAbstract:The present paper deals with the study of Rayleigh-Taylor instability at the cylindrical interface using viscous Potential Flow Theory. In the inviscid Potential Flow Theory, the viscous term in Navier-Stokes equation vanishes as viscosity is zero. In viscous Potential Flow, the viscous term in Navier-Stokes equation vanishes as vorticity is zero but viscosity is not zero. Viscosity enters through normal stress balance in viscous Potential Flow Theory and tangential stresses are not considered. A dispersion relation is derived and stability is discussed in terms of various parameters such as Ohnesorge number, density ratio etc. A condition for neutral stability is obtained and it is given in terms of critical value of the wave number. It is observed that the Ohnesorge number has destabilizing effect while inner fluid fraction has stabilizing effect on the stability of the system.
