In this paper, an innovative methodology to handle the numerical simulation of viscoplastic flows... more In this paper, an innovative methodology to handle the numerical simulation of viscoplastic flows is proposed based on a multigrid initialization algorithm in conjunction with the SIMPLE procedure. The governing equations for incompressible flow, which consist of continuity and momentum equations, are solved on a collocated grid by combining the finite volume discretization and Rhie and chow interpolation for pressure–velocity coupling. Using the proposed solver in combination with the regularization scheme of Papanastasiou, we chose the square lid-driven cavity flow and pipe flow as test cases for validation and discussion. In doing so, we study the influence of the Bingham number and the Reynolds number on the development of rigid areas and the features of the vortices within the flow domain. Pipe flow results illustrate the flow’s response to the stress growth parameter values. We show that the representation of the yield surface and the plug zone is influenced by the chosen valu...
Fluid transient analysis is one of the more challenging and complicated flow problems in the desi... more Fluid transient analysis is one of the more challenging and complicated flow problems in the design and the operation of water pipeline systems (wps). When transient conditions "water hammer" exists, the life expectancy of the wps can be adversely impacted, resulting in pump and valve failures and catastrophic pipe ruptures. Transient control has become an essential requirement for ensuring safe operation of wps. An accurate analysis and suitable protection devices should be used to protect wps. This paper presents the problem of modeling and simulation of transient phenomena in wps based on the characteristics method. Also, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occur in the transient. The developed model applied for main wps: pump combined with closed surge tank connected to a reservoir. The results obtained provide that the model is an efficient tool for water hammer analysis. Moreover; ...
This paper presents the problem of modeling and simulating of transient phenomena in conveying pi... more This paper presents the problem of modeling and simulating of transient phenomena in conveying pipeline systems based on the rigid column and full elastic methods. Transient analysis is important and one of the more challenging and complicated flow problem in the design and the operation of water pipeline systems. Transient can produce large pressure forces and rapid fluid acceleration into a water pipeline system, these disturbances may result in device failures, system fatigue or pipe ruptures, and even the dirty water intrusion. Several methods have been introduced and used to analyze transient flow, an accurate analysis and suitable protection devices should be used to protect water pipeline systems. The fourth-order Runge-Kutta method has been used to solve the dynamic and continuity equations in the rigid column method, while the characteristics method used to solve these equations in the full elastic method. The results obtained provide that the model is an efficient tool for...
Desurging tank with automatic air control "DTAAC" is a water hammer protection device, ... more Desurging tank with automatic air control "DTAAC" is a water hammer protection device, operates either an open or closed surge tank according to the water level inside the surge tank, with the volume of air trapped in the filling phase, this protection device has the advantages of its easy maintenance, and does not need to run any external energy source (air compressor). A computer program has been developed based on the characteristic method to simulate flow transient phenomena in pressurized water pipeline systems, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occurring in this phenomena. The developed model applied to a simple main water pipeline system: pump combined with DTAAC connected to a reservoir. The results obtained provide that the model is an efficient tool for water hammer analysis. Moreover; using the DTAAC reduces the unfavorable effects of the transients.
In water pipeline systems, the flow control is an integrated part of the operation, for instance,... more In water pipeline systems, the flow control is an integrated part of the operation, for instance, opening and closing the valves, starting and stopping the pumps, when these operations very quickly performed, they shall cause the hydraulic transient phenomena, which may cause pump and, valve failures and catastrophic pipe ruptures. Fluid transient analysis is one of the more challenging and complicated flow problems in the design and the operation of water pipeline systems. Transient control has become an essential requirement for ensuring safe operation of water pipeline systems. An accurate analysis and suitable protection devices should be used to protect water pipeline systems. The fourth-order Runge-Kutta method has been used to solve the dynamic and continuity equations in the rigid column method, while the characteristics method used to solve these equations in the full elastic methods. This paper presents the problem of modeling and simulating of transient phenomena in conve...
This paper presents some new applications of a coupled BEM/optimization technique for solution of... more This paper presents some new applications of a coupled BEM/optimization technique for solution of fluid flow problems with a free surface. The problems considered herein are the flow over a spillway and seepage through an earth dam. An iterative procedure combining the BEM and a nonlinear programming algorithm is used to determine the free surface location and the flow discharge over a spillway.
Abstract. With the development of remote sensing technology, several spatial sources for measurin... more Abstract. With the development of remote sensing technology, several spatial sources for measuring precipitation have become available: Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data are of particular interest. The CHIRPS product was used, evaluated, and compared within the Tensift basin located in west-central Morocco, for the period 1990 to 2017, using 11 meteorological stations. Four statistical parameters were used to evaluate CHIRPS performance, namely rain gauge measurements at multiple time scales (monthly, seasonal, and annual). Using the standard precipitation index as a drought indicator, the applicability of this long-term satellite precipitation product for drought monitoring was investigated for the period 1981 to 2019. The results show close agreement with observed precipitation data at different time scales (monthly, seasonal, and annual). At the monthly scale, the correlation coefficients vary between 0.56 and 0.86. In addition, a better cor...
An analysis of free boundary value problems for the steady, irrotational, plane flow of an invisc... more An analysis of free boundary value problems for the steady, irrotational, plane flow of an inviscid, incompressible fluid was performed using an h-adaptive boundary element method. The error estimator and indicator used in the adaptive scheme are based on computation of the residual function. Two approaches for computing predicted errors were used: Gauss quadrature [1] and Rank's scheme [2], with errors defined either in the L* or H* norms. Adjustment of the free surface has been made using iterative numerical procedures [3, 4]. Numerical results for two different cases: a sluice gate flow and a torrential flow, are presented at the end of the paper. INTRODUCTION The difficulty of modelling free surface problems is associated to the nonlinearity of the free surface boundary conditions, the unknown location of the free surface which has to be determined as part of the solution, and to possible singularities or discontinuities at the intersection between free surfaces and fixed on...
A BEM formulation of free boundary value problems for a class of steady, irrotational, plane flow... more A BEM formulation of free boundary value problems for a class of steady, irrotational, plane flow of an inviscid, incompressible fluid was developed using hadaptive algorithms to determine an optimal discretization, and a Gauss-Newton optimization technique to adjust the free surface location. Numerical results are presented for three different problems: flow past a vertical sluice gate, supercritical flow over an obstacle, and Riabouchinsky cavity flow.
A computer model for assessing the reliability of water-distribution networks is presented. Both ... more A computer model for assessing the reliability of water-distribution networks is presented. Both mechanical failure caused by pipe breakages and hydraulic failure caused by insufficient pipe capacity are incorporated into a simple stochastic model. A network solver identifies nodal pressures for individual pipe-failure conditions over a range of network demands, where both pipe failure and network demand are of known probabilities. The probabilities of pressure deficiency at nodes are calculated, from which the availability of supply is determined. Two examples are presented to clarify the principles of the model and to demonstrate the practicality of its applications. The model was developed to enable rapid yet realistic analysis of the reliability of water-distribution networks, and can be used for analyzing either existing systems or proposed designs of new systems.
This work contains sections of the edited Proceedings of the Second International Conference in C... more This work contains sections of the edited Proceedings of the Second International Conference in Computer Methods and Water Resources held at Marrakesh from February 20-22, 1991. It is divided into three volumes, the contents of which are classified in the following way: volume 1, entitled "Groundwater Modelling and Pressure Flow"; volume 2, entitled "Computational Hydraulics and Hydrology"; and volume 3, entitled "Computer Aided Engineering in Water Resources". This particular volume, volume 3, is concerned with water resource planning and management, computer aided engineering systems, data acquisition and processing, remote sensing, hydraulic structures and boundary element methods. This three-volume set on the Marrakesh conference proceedings on water resources, engineering, hydraulics and hydrology and civil engineering is intended for graduate engineers, researchers, environmentalists, applied mathematicians and civil engineers.
In this paper, an innovative methodology to handle the numerical simulation of viscoplastic flows... more In this paper, an innovative methodology to handle the numerical simulation of viscoplastic flows is proposed based on a multigrid initialization algorithm in conjunction with the SIMPLE procedure. The governing equations for incompressible flow, which consist of continuity and momentum equations, are solved on a collocated grid by combining the finite volume discretization and Rhie and chow interpolation for pressure–velocity coupling. Using the proposed solver in combination with the regularization scheme of Papanastasiou, we chose the square lid-driven cavity flow and pipe flow as test cases for validation and discussion. In doing so, we study the influence of the Bingham number and the Reynolds number on the development of rigid areas and the features of the vortices within the flow domain. Pipe flow results illustrate the flow’s response to the stress growth parameter values. We show that the representation of the yield surface and the plug zone is influenced by the chosen valu...
Fluid transient analysis is one of the more challenging and complicated flow problems in the desi... more Fluid transient analysis is one of the more challenging and complicated flow problems in the design and the operation of water pipeline systems (wps). When transient conditions "water hammer" exists, the life expectancy of the wps can be adversely impacted, resulting in pump and valve failures and catastrophic pipe ruptures. Transient control has become an essential requirement for ensuring safe operation of wps. An accurate analysis and suitable protection devices should be used to protect wps. This paper presents the problem of modeling and simulation of transient phenomena in wps based on the characteristics method. Also, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occur in the transient. The developed model applied for main wps: pump combined with closed surge tank connected to a reservoir. The results obtained provide that the model is an efficient tool for water hammer analysis. Moreover; ...
This paper presents the problem of modeling and simulating of transient phenomena in conveying pi... more This paper presents the problem of modeling and simulating of transient phenomena in conveying pipeline systems based on the rigid column and full elastic methods. Transient analysis is important and one of the more challenging and complicated flow problem in the design and the operation of water pipeline systems. Transient can produce large pressure forces and rapid fluid acceleration into a water pipeline system, these disturbances may result in device failures, system fatigue or pipe ruptures, and even the dirty water intrusion. Several methods have been introduced and used to analyze transient flow, an accurate analysis and suitable protection devices should be used to protect water pipeline systems. The fourth-order Runge-Kutta method has been used to solve the dynamic and continuity equations in the rigid column method, while the characteristics method used to solve these equations in the full elastic method. The results obtained provide that the model is an efficient tool for...
Desurging tank with automatic air control "DTAAC" is a water hammer protection device, ... more Desurging tank with automatic air control "DTAAC" is a water hammer protection device, operates either an open or closed surge tank according to the water level inside the surge tank, with the volume of air trapped in the filling phase, this protection device has the advantages of its easy maintenance, and does not need to run any external energy source (air compressor). A computer program has been developed based on the characteristic method to simulate flow transient phenomena in pressurized water pipeline systems, it provides the influence of using the protection devices to control the adverse effects due to excessive and low pressure occurring in this phenomena. The developed model applied to a simple main water pipeline system: pump combined with DTAAC connected to a reservoir. The results obtained provide that the model is an efficient tool for water hammer analysis. Moreover; using the DTAAC reduces the unfavorable effects of the transients.
In water pipeline systems, the flow control is an integrated part of the operation, for instance,... more In water pipeline systems, the flow control is an integrated part of the operation, for instance, opening and closing the valves, starting and stopping the pumps, when these operations very quickly performed, they shall cause the hydraulic transient phenomena, which may cause pump and, valve failures and catastrophic pipe ruptures. Fluid transient analysis is one of the more challenging and complicated flow problems in the design and the operation of water pipeline systems. Transient control has become an essential requirement for ensuring safe operation of water pipeline systems. An accurate analysis and suitable protection devices should be used to protect water pipeline systems. The fourth-order Runge-Kutta method has been used to solve the dynamic and continuity equations in the rigid column method, while the characteristics method used to solve these equations in the full elastic methods. This paper presents the problem of modeling and simulating of transient phenomena in conve...
This paper presents some new applications of a coupled BEM/optimization technique for solution of... more This paper presents some new applications of a coupled BEM/optimization technique for solution of fluid flow problems with a free surface. The problems considered herein are the flow over a spillway and seepage through an earth dam. An iterative procedure combining the BEM and a nonlinear programming algorithm is used to determine the free surface location and the flow discharge over a spillway.
Abstract. With the development of remote sensing technology, several spatial sources for measurin... more Abstract. With the development of remote sensing technology, several spatial sources for measuring precipitation have become available: Climate Hazards Group Infrared Precipitation with Stations (CHIRPS) data are of particular interest. The CHIRPS product was used, evaluated, and compared within the Tensift basin located in west-central Morocco, for the period 1990 to 2017, using 11 meteorological stations. Four statistical parameters were used to evaluate CHIRPS performance, namely rain gauge measurements at multiple time scales (monthly, seasonal, and annual). Using the standard precipitation index as a drought indicator, the applicability of this long-term satellite precipitation product for drought monitoring was investigated for the period 1981 to 2019. The results show close agreement with observed precipitation data at different time scales (monthly, seasonal, and annual). At the monthly scale, the correlation coefficients vary between 0.56 and 0.86. In addition, a better cor...
An analysis of free boundary value problems for the steady, irrotational, plane flow of an invisc... more An analysis of free boundary value problems for the steady, irrotational, plane flow of an inviscid, incompressible fluid was performed using an h-adaptive boundary element method. The error estimator and indicator used in the adaptive scheme are based on computation of the residual function. Two approaches for computing predicted errors were used: Gauss quadrature [1] and Rank's scheme [2], with errors defined either in the L* or H* norms. Adjustment of the free surface has been made using iterative numerical procedures [3, 4]. Numerical results for two different cases: a sluice gate flow and a torrential flow, are presented at the end of the paper. INTRODUCTION The difficulty of modelling free surface problems is associated to the nonlinearity of the free surface boundary conditions, the unknown location of the free surface which has to be determined as part of the solution, and to possible singularities or discontinuities at the intersection between free surfaces and fixed on...
A BEM formulation of free boundary value problems for a class of steady, irrotational, plane flow... more A BEM formulation of free boundary value problems for a class of steady, irrotational, plane flow of an inviscid, incompressible fluid was developed using hadaptive algorithms to determine an optimal discretization, and a Gauss-Newton optimization technique to adjust the free surface location. Numerical results are presented for three different problems: flow past a vertical sluice gate, supercritical flow over an obstacle, and Riabouchinsky cavity flow.
A computer model for assessing the reliability of water-distribution networks is presented. Both ... more A computer model for assessing the reliability of water-distribution networks is presented. Both mechanical failure caused by pipe breakages and hydraulic failure caused by insufficient pipe capacity are incorporated into a simple stochastic model. A network solver identifies nodal pressures for individual pipe-failure conditions over a range of network demands, where both pipe failure and network demand are of known probabilities. The probabilities of pressure deficiency at nodes are calculated, from which the availability of supply is determined. Two examples are presented to clarify the principles of the model and to demonstrate the practicality of its applications. The model was developed to enable rapid yet realistic analysis of the reliability of water-distribution networks, and can be used for analyzing either existing systems or proposed designs of new systems.
This work contains sections of the edited Proceedings of the Second International Conference in C... more This work contains sections of the edited Proceedings of the Second International Conference in Computer Methods and Water Resources held at Marrakesh from February 20-22, 1991. It is divided into three volumes, the contents of which are classified in the following way: volume 1, entitled "Groundwater Modelling and Pressure Flow"; volume 2, entitled "Computational Hydraulics and Hydrology"; and volume 3, entitled "Computer Aided Engineering in Water Resources". This particular volume, volume 3, is concerned with water resource planning and management, computer aided engineering systems, data acquisition and processing, remote sensing, hydraulic structures and boundary element methods. This three-volume set on the Marrakesh conference proceedings on water resources, engineering, hydraulics and hydrology and civil engineering is intended for graduate engineers, researchers, environmentalists, applied mathematicians and civil engineers.
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