The Experts below are selected from a list of 51 Experts worldwide ranked by ideXlab platform
Fan Leilei - One of the best experts on this subject based on the ideXlab platform.
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Investigation into Complex Boundary Solutions of Water Filling Process in Pipeline Systems
Water, 2019Co-Authors: Zhang Boran, Wan Wuyi, Fan LeileiAbstract:Boundary conditions are usually the key problem in the establishment of a numerical model for simulation. An algorithmic method is needed to obtain a concrete numerical solution when the combined controlling equation sets are difficult to solve analytically. In this research, a type of algorithm known as the double forward method (DFM) is proposed to solve complex Boundary conditions. The accuracy of the DFM is controllable, and it was found to be reliable when applying it to the water filling process in a water supply pipeline system. The DFM can also be used to solve multidimensional problems. In addition, the established water filling model in this study combined an open channel flow and a pressured flow, and a surge Tank Boundary condition was developed to fit the entire water filling process.
H. Soleimani - One of the best experts on this subject based on the ideXlab platform.
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An analytical solution for free liquid sloshing in a finite-length horizontal cylindrical container filled to an arbitrary depth
Applied Mathematical Modelling, 2017Co-Authors: Seyyed M. Hasheminejad, H. SoleimaniAbstract:Abstract A general series-type theoretical formulation based on the linearized potential theory, the method of separation of variables, and the translational addition theorem for cylindrical Bessel functions is developed to study three-dimensional natural sloshing in a partially filled horizontally-mounted circular cylindrical Tank of finite span. Assuming time-harmonic variations, the potential solutions associated with the Symmetric/Antisymmetric (S/A) modes of free liquid surface oscillations are first analytically expanded as series of bounded spatial functions with unknown modal coefficients. The impenetrability conditions of the rigid end-plates along with the free surface dynamic/kinematic Boundary condition are then imposed. The zero-normal-velocity requirement of the lateral Tank Boundary is subsequently applied by innovative use of Graf's translational addition theorem for modified cylindrical Bessel functions. After truncation, four independent sets of homogeneous algebraic equations are obtained that are then numerically worked out for the natural sloshing eigen-frequencies and free surface oscillation mode shapes. Extensive numerical data include the first thirty six longitudinal/transverse Antisymmetric/Symmetric (AA, SA, AS, SS) dimensionless sloshing frequencies, for a wide range of liquid fill depths and container span to radius ratios. Also, the influence of fill depth on the free surface oscillation mode shapes is addressed through selected 2D images. Comprehensive numerical simulations illustrate the strong effects of container length and liquid fill depth on the calculated sloshing frequencies. It is revealed that the frequency branches with the same transverse mode number form a cluster that progressively merge together amid the Tank fill-depth limits as the Tank span ratio increases. On the other hand, when the Tank length substantially decreases, the number of “frequency cross-overs” between various frequency clusters at certain liquid fill depths considerably increases. Moreover, primary advantages of proposed methodology in comparison to other approximate/numerical methods are explicitly pointed out, convergence of solution is tested, and accuracy/reliability of the results is demonstrated by comparisons with available data.
Zhang Boran - One of the best experts on this subject based on the ideXlab platform.
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Investigation into Complex Boundary Solutions of Water Filling Process in Pipeline Systems
Water, 2019Co-Authors: Zhang Boran, Wan Wuyi, Fan LeileiAbstract:Boundary conditions are usually the key problem in the establishment of a numerical model for simulation. An algorithmic method is needed to obtain a concrete numerical solution when the combined controlling equation sets are difficult to solve analytically. In this research, a type of algorithm known as the double forward method (DFM) is proposed to solve complex Boundary conditions. The accuracy of the DFM is controllable, and it was found to be reliable when applying it to the water filling process in a water supply pipeline system. The DFM can also be used to solve multidimensional problems. In addition, the established water filling model in this study combined an open channel flow and a pressured flow, and a surge Tank Boundary condition was developed to fit the entire water filling process.
Seyyed M. Hasheminejad - One of the best experts on this subject based on the ideXlab platform.
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An analytical solution for free liquid sloshing in a finite-length horizontal cylindrical container filled to an arbitrary depth
Applied Mathematical Modelling, 2017Co-Authors: Seyyed M. Hasheminejad, H. SoleimaniAbstract:Abstract A general series-type theoretical formulation based on the linearized potential theory, the method of separation of variables, and the translational addition theorem for cylindrical Bessel functions is developed to study three-dimensional natural sloshing in a partially filled horizontally-mounted circular cylindrical Tank of finite span. Assuming time-harmonic variations, the potential solutions associated with the Symmetric/Antisymmetric (S/A) modes of free liquid surface oscillations are first analytically expanded as series of bounded spatial functions with unknown modal coefficients. The impenetrability conditions of the rigid end-plates along with the free surface dynamic/kinematic Boundary condition are then imposed. The zero-normal-velocity requirement of the lateral Tank Boundary is subsequently applied by innovative use of Graf's translational addition theorem for modified cylindrical Bessel functions. After truncation, four independent sets of homogeneous algebraic equations are obtained that are then numerically worked out for the natural sloshing eigen-frequencies and free surface oscillation mode shapes. Extensive numerical data include the first thirty six longitudinal/transverse Antisymmetric/Symmetric (AA, SA, AS, SS) dimensionless sloshing frequencies, for a wide range of liquid fill depths and container span to radius ratios. Also, the influence of fill depth on the free surface oscillation mode shapes is addressed through selected 2D images. Comprehensive numerical simulations illustrate the strong effects of container length and liquid fill depth on the calculated sloshing frequencies. It is revealed that the frequency branches with the same transverse mode number form a cluster that progressively merge together amid the Tank fill-depth limits as the Tank span ratio increases. On the other hand, when the Tank length substantially decreases, the number of “frequency cross-overs” between various frequency clusters at certain liquid fill depths considerably increases. Moreover, primary advantages of proposed methodology in comparison to other approximate/numerical methods are explicitly pointed out, convergence of solution is tested, and accuracy/reliability of the results is demonstrated by comparisons with available data.
Gautam Biswas - One of the best experts on this subject based on the ideXlab platform.
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steady separated flow past a circular cylinder at low reynolds numbers
Journal of Fluid Mechanics, 2009Co-Authors: Subhankar Sen, Sanjay Mittal, Gautam BiswasAbstract:The steady two-dimensional laminar flow around a stationary circular cylinder has been investigated via a stabilized finite-element method. The Reynolds number Re is based on the cylinder diameter and free-stream speed. The results have been presented for 6 ≤ Re ≤ 40 and the blockages between 0.000125 and 0.80. The blockage B is the ratio of the cylinder diameter to the domain width. There is large scatter in the value of Re s , reported in the literature, marking the onset of the flow separation. From the present study the Re s is found to be 6.29, approximately for B = 0.005. The effect of the blockage on the characteristic flow parameters is found to be insignificant for B ≤ 0.01. The bubble length, separation angle and Re s exhibit non-monotonic variation with the blockage. It is for the first time that such a behaviour for the separation angle and Re s is being reported. Two types of Boundary conditions at the lateral walls have been studied: the slip wall and towing Tank. In general for high blockage, the results from the slip Boundary condition are closer to the ones for the unbounded flow. In that sense, the use of the slip Boundary condition as opposed to the towing Tank Boundary condition on the lateral walls is advocated. The bubble length, separation angle, base suction, total drag, pressure drag, viscous drag and maximum vorticity on the cylinder surface for the steady flow are found to vary as Re , Re −0.5 , Re −1 , Re −0.5 , Re −0.64 , Re −0.60 and Re 0.5 , respectively. The extrapolated results for the steady flow, for higher Re , are found to match quite well with the other results from the literature.
