Abdellatif Ouahsine

University of Technology of Compiègne | UTC · Ingénierie Mécanique (IM). Lab Roberval

In inland waterways, waves generated by passing boats cause the movement of riprap used for bank protection and stabilization. Previous studies have mainly concerned the natural channel erosion problem caused by wind-generated waves and neglected the research and findings on shipping behavior. This work presents a coupling of the computational flui...

An improved implicit direct-forcing immersed boundary method (DF-IBM) is presented for simulating incompressible flows around complex rigid structures undergoing arbitrary motion. The current approach harnesses the pressure implicit with splitting of operators algorithm to handle the fluid–solid system's dual constraints in a segregated manner. As...

The density of the ocean is unevenly distributed along the depth direction, showing a stratified structure. When there is an external disturbance, large-scale internal solitary waves are easily generated. The internal solitary waves are bounded by the intermediate pycnocline, and the currents in the upper and lower layers will flow in opposite dire...

This paper examines the response characteristics of a warship’s double-layer plates under a secondary near-field explosion after the ship’s outer plate has been perforated by shaped metal jets. First, the effectiveness of the Coupled Eulerian–Lagrangian (CEL) method was validated, showing numerical simulations to be well aligned with experimental r...

Dear Colleagues, Computational fluid dynamics (CFD) methods play important roles for the design and ability assessment of marine vehicles, structures, ships, etc. They are widely used in the fields of naval architecture and ocean engineering. Nowadays, CFD techniques have developed to a very high level. They can partly or even fully replace experim...

Dear Colleagues, In recent years, the applications of CFD simulations to marine hydrodynamics and marine engineering problems have grown considerably. This Special Issue responds to the need for a textbook that unifies various issues on the applications of CFD simulations to marine hydrodynamics problems, and also to applications of fluid-structure...

Dear Colleagues, In recent years, the applications of CFD simulations to marine hydrodynamics and marine engineering problems have grown considerably. This Special Issue responds to the need for a textbook that unifies various issues on the applications of CFD simulations to marine hydrodynamics problems, and also to applications of fluid-structure...

Dear Colleagues, Fluid flows and their interactions with structures are of great importance in both fundamental research and engineering applications. Revealing their mechanisms inevitably involves fluid mechanics. Computational fluid mechanics techniques are developing to a higher level today with the flourishing of computer science. It is able to...

Ocean flows and their interactions with marine structures, vehicles, etc., are of great importance for the research of marine science and technology. The revealing of their mechanisms inevitably involves fluid mechanics. Computational fluid mechanics techniques are developing to a higher level nowadays, with the flourishing of computer science. It...

A three-dimensional numerical simulation method based on the resolution of Navier–Stokes equations is used to determine the causal relationship between the ship-induced waves and the erosion phenomenon of the inland waterway banks, and also to provide the critical conditions for waterway bank protection. The erosion process of the bank is defined h...

The maneuvering simulation is carried out through the continuous captive model test and the system dynamics approach. The mathematical maneuvering group (MMG) model is implemented in the virtual captive model tests by using the computational fluid dynamics (CFD) techniques. The oblique towing test (OTT), the circular motion test (CMT), the rudder f...

A strongly coupled algorithm is presented for the incompressible fluid-rigid body interaction using the moving immersed boundary method. The pressure and the boundary force are treated as Lagrange multipliers to enforce the incompressibility and no-slip wall constraints. To compute the two unknowns from the velocity field, we adopt the fractional s...

The average and unsteady hydrodynamics of an inland convoy passing bridge piers in a confined waterway were investigated using both numerical and experimental approaches. The numerical simulations are realized by solving the RANS (Reynolds-averaged Navier–Stokes) equations accounting for the solid body motion using the sliding mesh technique, while...

Special issue "Computational Fluid Mechanics" in the Journal of Marine Science and Engineering

A numerical study using the Discontinuous Deformation Analysis (DDA) method is proposed to analyze the effect of the caisson sliding subjected to a hydrodynamic loading in the stability of the rear side of the caisson-type breakwater. The study takes into account the slope inclination of the breakwater as well as the contact between the armour uni...

Breakwaters are used for the protection of harbors and beaches against wave action. This paper focuses on the analysis of the stability of the caisson-type breakwater under Flip-through wave impacts using a coupled Fluid-Porous model. The fluid hydrodynamic is described by the Volume-averaged Reynolds-Averaged Navier-Stokes (VARANS) equation with k...

Wave impacts on vertical caissons may cause breakwaters failures. This paper focuses on the analysis of the stability of breakwaters under violent wave impacts by using a triple-coupled Fluid-Porous-Solid model. The fluid model is described by the Volume-Averaged Reynolds-Averaged Navier-Stokes equations in which the nonlinear Forchheimer equations...

Environmental effects on ship hydrodynamics during inland waterway transport are investigated using both CFD (Computational Fluid Dynamics) and towing tank experiments. Three important scenes, the confinement effect of the waterway, head-on encounter and ship-bridge pier interactions are studied. The testing conditions cover a wide range, including...

The resistance and ship-generated waves of two inland vessels in the fully-confined waterway are investigated based on numerical simulations. The simulation results are validated using towing tank experiments. The influences of the channel dimension, water depth, ship draught and velocity are studied. Specially, the ship resistance is characterized...

Frozen snow/ice blocks drop at high speeds from train causing the ballast to fly up and damage the car body. Thus, in this paper, we propose a numerical model based on the discontinuous deformation analysis (DDA) method to study the ballast flight caused by dropping snow/ice blocks in high-speed railways and to analyze the dynamic behavior of balla...

The overtaking maneuver of two Esso Bernicia 1.9×105 DWT tankers was investigated using the system-based maneuvering method. The Brix model was incorporated to account for the overtaking interactions. Forces/moment acting on the ship hulls and maneuvering motions were analyzed for both ships during the overtaking. The influences of the speed ratio...

A six-Dof motion solver based on unit quaternions and an actuator disk model are implemented for ship hydrodynamics predictions. The six-Dof module is tested using the water entry phenomenon of a free falling sphere. The displacement history and impacting forces are analyzed. A KCS (KRISO container ship) model with the allowances of sinkage and tri...

The ship hydrodynamics in static and dynamic states were investigated using 3-dimensional numerical simulations. The static case simulated a fixed ship, while the dynamic case considered a ship with free sinkage and trim using the mesh morphing technique. High speed was found to increase the wave elevation around the ship. Compared with the static...

Ship maneuvering in the confined inland waterway is investigated using the system-based method, where a nonlinear transient hydrodynamic model is adopted and confinement models are implemented to account for the influence of the channel bank and bottom. The maneuvering model is validated using the turning circle test, and the confinement model is v...

A novel implicit immersed boundary method of high accuracy and efficiency is presented for the simulation of incompressible viscous flow over complex stationary or moving solid boundaries. A boundary force is often introduced in many immersed boundary methods to mimic the presence of solid boundary, such that the overall simulation can be performed...

A novel immersed boundary method is introduced for simulating the fluid-structure interaction problem. Unlike the body-conforming mesh method which imposes the no-slip boundary conditions directly on the immersed interface, the immersed boundary method adopts a boundary force for the presence of the immersed solid. Therefore, the fluid is simply si...

A three-dimensional (3D) hydrodynamic numerical model is proposed to predict ship resistance and sinkage of an inland vessel sailing in restricted waterways. The flow around the ship is simulated, and the hydrodynamic forces acting on the hull are calculated. A quasi-Newton method is applied to find the vertical equilibrium position and to update t...

Vessels such as towboats and barges can generate wake waves, cause draw-down and send waves back along riverbanks in narrow channel areas, and also contribute to sediment re-suspension and riverbank erosion. This chapter presents a three-dimensional (3D) numerical model based on coupling a 3D Reynolds averaged Navier-Stokes (RANS) equation and a se...

The mutual interaction between floods and human activity is a process, which has been evolving over history and has shaped flood risk pathways. In developed countries, many events have illustrated that the majority of the fatalities during a flood occurs in a vehicle, which is considered as a safe shelter but it may turn into a trap for several com...

In the current paper, a numerical model for simulating the ocean wave energy conversion of a semi-submerged heaving cylinder is presented. Contrary to the convectional potential flow theory, our solution is based on the full three-dimensional viscous Navier-Stokes equations. An efficient numerical wave tank is established to generate waves accordin...

We present an implicit immersed boundary method via operator splitting technique for simulating fluid flow over moving solid with complex shape. An additional moving force equation is derived in order to impose the interface velocity condition exactly on the immersed surface. The moving force matrix is formulated to be symmetric and positive defini...

A modeling system integrating river and watershed, capable of simulating overland flow and surface runoff in natural streams, is proposed. This model is based on the coupling of two models: a 2D-model for the flow in the plain and a ID- model for the river flow. It constitutes a possible alternative to conceptual models with lockers, which are base...

Accurate prediction of hydrodynamic forces opposing a ship displacement in restricted waterways is necessary in order to improve energy efficiency of inland transport. When a ship moves in restricted waterways, a significant increase in ship squat (combination of sinkage and trim) and resistance occurs compared to a movement in open waters. In this...

We present the numerical simulation of lid-driven cavity flow with an embedded cylinder by using a modified implicit immersed boundary method. The immersed boundary method features the non body-conforming mesh merit, which facilitates the simulation with complex geometry in a flow. The paper compares the numerical solutions between the modified imp...

This paper presents a numerical investigation of ship maneuvering under the combined effect of the bank and propeller. The incompressible turbulent flow with free surface around the self-propelled hull form is simulated using a commercial CFD software (Fluent). In order to estimate the dynamic effect of bank and propeller, the CFD model with the dy...

This Erratum concerns the correction of the momentum equation (3) in [1] and then, Eqs. (9), (13) and (16). This correction does not affect in any way the validity of the mathematical analysis of the rest of the original version of the paper [1].

In inland waterways, the wave wake is the main factor that erodes the banks and the alluvial bottom. It may cause sediment resuspension into the water column. A 3D hydrodynamic model based on the Navier-Stokes equations is developed to reproduce these wave wakes and analyze their kinematic characteristics. Then, a 3D model of sediment transport is...

The duration of ship-generated waves (wake waves) and accelerated currents can generate significant influences on the sediment transport. A 3-D numerical model is presented to estimate these effects. The hydrodynamic model is the 3-D Reynolds averaged Navier-Stokes (RANS) equations including the standard k – ɛ model while the 3-D convection-diffusi...

A novel efficient implicit direct forcing immersed boundary method for incompressible flows with complex boundaries is presented. In the previous work [1], the calculation is performed on the Cartesian grid regardless of the immersed object, with a fictitious force evaluated on the Lagrangian points to mimic the presence of the physical boundaries....

Ship-generated waves and return currents are capable of re-suspending significant quantities of bottom and bank sediments. However, most of the previous studies done on the subject do not show how and where sediment is re-suspended by the wakes and the directions of net transport. In this paper, a 3D numerical model based on hydro-sedimentary coupl...

The strengthening of the conventional 2D laminates by transverse seams has been developed to compensate the inherent weakness of these materials, such as the delaminating and impact behavior. Moreover, these seams play an important role in draining and improving the impregnation ability of the reinforcements. In this context, our study will focus o...

In this paper, a numerical method based on a coupling between a mathematical model of nonlinear transient ship manoeuvring motion in the horizontal plane and Mathematical Programming (MP) techniques is proposed. The aim of the proposed procedure is an efficient estimation of optimal ship hydrodynamic parameters in a dynamic model at the early desig...

Ship-generated waves and return currents are capable of resuspending significant quantities of bottom and bank sediments. However, most of the previous studies done on the subject do not show how and where sediment is resuspended by the wakes and the directions of net transport. In this paper, a three-dimensional (3D) numerical model based on hydro...

We present the Lattice Boltzmann method for modelling shallow water equations with a focus on external forces. Three different approximations for modelling the body force terms are used and compared in a 1D steady flow simulation over a bump. The accuracy, the mass conservation and the CPU time are discussed in this study.

In this paper, a numerical study is conducted to assess the stability of the seaward facing slope of breakwaters under hydrodynamic loading using a coupled fluid–structure interaction framework. Stability characteristics of breakwaters have traditionally been analysed using empirical approaches which do not take into account important factors such...

A numerical model based on the method of Discontinuous Deformation Analysis (DDA) is presented to simulate the stability of rubble-mound breakwaters. The breakwater is considered as a stack of rigid blocks moving against each other and subject to seismic loading. The contact and cohesion between blocks as well as the geometric shape of the blocks a...

We present a 2D numerical model based on the finite element method FEM to simulate the surface flow of Watershed model. The kinematic wave approximation describing surface water flow under constant rainfall rate with infiltration is considered. Slopes and roughness are varying in space, while rainfall intensity varies in time. Thus, sensitivity...

We consider waves generated by the passing of convoys in a restricted waterway. The magnitude of these waves depends mainly on the geometrical and kinematical parameters of the convoy, such as the speed and the hull geometry. The objective of this study is to predict the relationship between these geometrical and kinematical parameters and the ampl...

In this paper mathematical and numerical analyses are presented to investigate self-similarity solutions of a two-dimensional MHD boundary layer flow over a permeable surface. Required boundary conditions to obtain a similarity solution, are detailed. In the case of the Nonlinear Density Temperature (NDT) parameter, the self-similarity solution may...

We present a numerical model based on the hydro-morphodynamical coupling to study coastal sandbar migration. In order to improve both nonlinear and dispersive wave processes in relatively shallow water, we developed a finite element model based on the Legendre polynomials and on the Extended Boussinesq model. This model reproduces the propagation o...

The HySuf-FEM code (Hydrodynamic of Subsurface Flow by Finite Element Method) is proposed in this article in order to estimate the spatial variability of the transmissivity values of the Berrechid aquifer (Morocco). The calibration of the model is based on the hydraulic head, hydraulic conductivity and recharge. Three numerical tests are used to va...

In this research, two-dimensional mixed convection boundary-layer flow over a vertical flat plate embedded in a porous medium saturated with a water at 4°C (maximum density) and an applied magnetic field are investigated theoretically and numerically using the new Chebyshev pseudospectral differentiation matrix (ChPDM) approach introducing by Aly e...

A proper estimation of the skin shear stress τ s is necessary for a proper evaluation of sediment flux at the sediment–fluid interface. Several empirical formulas of the skin shear stress have been proposed in the literature for rippled bed as function of the factor form η/λ (η and λ are respectively the height and wavelength of the bedform). These...

We propose a new mixing length profile, based on an extension of von K\'arm\'an similarity hypothesis, as well as the associated mixing velocity profile. This profile was compared with other profiles and was tested on three academic and experimental cases. The validation of the model was made from a set of reference examples and concerns the erosio...

Solving problems with free surface often encounters numerical difficulties related to excessive mesh distortion as is the case of dambreak or breaking waves. In this paper the Natural element method (NEM) is used to simulate a 2D shallow water flows in the presence of theses strong gradients. This particle-based method used a fully Lagrangian formu...

The frequency of ship grounding and collisions led to model the various factors involved during the course of a maneuvering ship. In this paper we present a numerical procedure to identify the hydrodynamic coefficients for a free-running ship by coupling the ship motion model and the optimization techniques. To accurate modeling of hydrodynamic par...

Un couplage fluide-structure est proposé pour étudier la stabilité des digues en enrochement sous les effets hydrodynamiques de la houle et des courants. Un code en éléments finis de Navier-Stokes pour le calcul fluide est alors couplé à un code pour le calcul solide basé sur la méthode de l’Analyse de Déformation Discontinue (DDA). Le but est de s...

In this paper, we present a 2D coupled fluid-structure interaction procedure to assess the stability of a cracked gravity dam against increasing water level. In this procedure the structure is assumed to be a discontinuous deformable solid containing pre-existing cracks. Thus, the Discontinuous Deformation Analysis DDA method is used to study the s...

3D Numerical investigations of ship-induced waves in restricted waterways by Radioss

Ship-generated gravity waves caused by a moving vessel in a restricted channel are simulated by solving three dimensional Navier-Stokes equations including the SST k - ω/ε model for turbulence processes. The main objective of this contribution is to predict the relationship between the magnitude of these waves and the geometrical and kinematical pa...

In this paper, we present a 2D coupled fluid-structure interaction procedure to assess the stability of a cracked gravity dam against increasing water level. In this procedure the structure is assumed to be a discontinuous deformable solid containing pre-existing cracks. Thus, the Discontinuous Deformation Analysis DDA method is used to study the s...

The Natural Element Method (NEM) is used to simulate a 2D shallow water flow in presence of free surface and a varying bathymetry. This meshless method used a fully Lagrangian formulation and natural neighbors, which remain a very striking problem related the boundary conditions. The method was succefully used to simulate dam-break flows by solving...

This paper concerns the numerical schemes describing solute transport in fissured systems which are characterized by the tectonic blocks and spatial repartition of hydraulic properties with dual permeability structures composed of high- and low-permeability blocks of the chalk aquifer (Northern France). Both advection and diffusion mechanisms are t...

This study deals with the simulation of transport and interaction between bodies considered as a rectangular shape particles, in urban flow. We used an hydrodynamic two-dimensional finite elements model coupled to the particles model based on Maxey-Riley equations, and taking into account of contact between bodies. The finite element discretization...

This study deals with the simulation of transport and interaction between bodies considered as a rectangular shape particles, in urban flow. We used an hydrodynamic two-dimensional finite elements model coupled to the particles model based on Maxey-Riley equations, and taking into account of contact between bodies. The finite element discretization...

In order to solve the advection-diffusion transport equations (ADTE), many flux-limiting schemes have been proposed. In most cases, monotony conditions for these schemes ignore the process of the physical diffusion. In this paper, we propose new flux-limiter functions depending on the physical diffusion to ensure TVD (Total Variation Diminishing) c...

The main limitation of the most common form of the equations of Boussinesq is that they are valid only for relatively shallow depth of water. In the present study, an innovative approach (h − s) based on the finite elements method is presented to improve the dispersion relationship. This approach, based on the so-called extended Boussinesq model, r...

We propose a new mixing length profile, based on an extension of von Kármán similarity hypothesis, as well as the associated mixing velocity profile. This profile was compared with other profiles and was tested on three academic and experimental tests. The validation of the model was made by considering two reference examples. The first example con...