A soleira lateral desempenha um papel importante nos reservatórios de detenção/ retenção (off-line), atuando na captação das vazões afluentes e evitando possíveis enchentes, problema em destaque nos períodos chuvosos das principais capitais brasileiras. Um melhor entendimento do seu comportamento hidráulico possibilitará o desenvolvimento de estruturas laterais mais eficientes. O presente trabalho tem como objetivo criar um modelo da soleira lateral através da tecnologia CFD (Dinâmica dos Fluidos Computacional) e validá-lo através de experimentos em modelo reduzido do Laboratório de Hidráulica da Escola Politécnica da USP. A partir disso, explorar as características hidráulicas do modelo de CFD, como o comportamento dos níveis dágua e a distribuição de velocidades. No estudo da validação estudaram-se três tipos de refinamento de malhas e três modelos de turbulência (k-, k- (RNG) e SST k-). O modelo computacional validado é composto pela malha 3, com um refinamento cerca de 342000 elementos (hexaédricos predominante), e o modelo de turbulência k- (RNG), que apresentaram a maior precisão dos resultados. A análise da distribuição de velocidades possibilitou visualizar uma região de mínima velocidade abaixo da soleira lateral, e também quantificar uma região de baixas velocidades no início da soleira, onde é pequena a eficiência das vazões escoadas. Através do comportamento da superfície dágua foi possível visualizar a região de influência do dispositivo lateral no canal principal. A comparação do coeficiente de descarga do modelo de CFD com trabalhos de outros pesquisadores, um nacional e outro internacional, mostrou a representatividade do modelo criado para condições diferentes. A ferramenta CFD é promissora para o estudo de estruturas hidráulicas, contribuindo para o seu desenvolvimento e aperfeiçoamento. / The side weir plays an important role in the detention / retention tanks (off-line), operating in the uptake of water inflow and preventing possible flooding, which is a highlighted problem on rainy periods of the main Brazilian capitals. A better understanding of the hydraulic behavior allows the development of more efficient lateral structures. This work aims at creating a model of the side weir through CFD technology (Computational Fluid Dynamics) and validating it through experiments on a reduced model of the Laboratório de Hidráulica da Escola Politécnica da USP. Thereafter, explore the hydraulic characteristics of the CFD model, like the behavior of water levels and the velocity distribution. In the validation study, three types of mesh refinement and three turbulence models were studied (k-, k- (RNG) and SST k-). The computational model is validated by the composite mesh 3 with a refinement about 342,000 elements (hexahedral predominant), and the turbulence model k- (RNG), which had the highest precision of results. Analysis of the velocities distribution allowed us to visualize a region of minimum velocity below the side weir, and also to quantify a region of low velocities at the beginning of the weir, where the efficiency of overflows is small. Through water surface behavior it was possible to visualize the influence region of the side device in the main channel. A comparison of discharge coefficient of the CFD model between other works (one national and the other one international) showed the representativeness of the model created for different conditions. The CFD is a promising tool for the study of hydraulic structures, contributing to its development and improvement.

A dynamic simulation of the response of an inflatable dam subjected to a flood was carried out to determine the survivability envelope of the dam where it can operate without rupture, or overflow. A fully nonlinear free-surface flow was applied in two dimensions using a mixed Eulerian-Lagrangian formulation. An ABAQUS finite element model was used to determine the dynamic structural response of the dam. The problem was solved in the time domain which allows the prediction of a number of transient phenomena such as the generation of upstream advancing waves, and dynamic structural collapse. Stresses in the dam material were monitored to determine when rupture occurs. An iterative study was performed to find the service envelope of the dam in terms of the internal pressure and the flood Froude number for two flood depths. It was found that the driving parameter governing failure of the dam was the internal pressure. If this pressure is too low, the dam overflows; if this pressure is too high, the dam ruptures. The fully nonlinear free-surface flow over a semi-circular bottom obstruction was studied numerically in two dimensions using a similar solution formulation as that used in the previous study. A parametric study was performed for a range of values of the depth-based Froude number up to 2.5 and non-dimensional obstacle heights up to 0.9. When wave breaking does not occur, three distinct flow regimes were identified: subcritical, transcritical and supercritical. When breaking occurs it may be of any type: spilling, plunging or surging. In addition, for values of the Froude number close to 1, the upstream solitary waves break. A systematic study was undertaken, to define the boundaries of each type of breaking and non-breaking pattern, and to determine the drag and lift coefficients, free surface profile characteristics and transient behavior. / Master of Science

The behaviour of free-surface gravity waves on small Froude number fluid flow past some obstacle cannot be determined using ordinary asymptotic power series methods, as the amplitude of the waves is exponentially small. An exponential asymptotic method is used by Chapman and Vanden-Broeck (2006) to consider the problem of two-dimensional, steady flow past a submerged obstacle in the small Froude number limit, finding that a steady downstream wavetrainis switched on rapidly across a curve known as a Stokes line. Here, equivalent wavetrains on three-dimensional and unsteady flow configurations are considered, and Stokes switching causedby the interaction between exponentially small free-surface components is shown to play an important role in both cases. The behaviour of free-surface gravity waves is introduced by considering the problem of steady free-surface flow due to a line source. A steady wavetrain is shown to exist in the far field, and the behaviour of these waves is compared to existing numerical results. The problem of unsteady flow over a step is subsequently investigated, with the flow behaviour formulated in terms of Lagrangian coordinates so that the position of the free surface is fixed. Initially, the problem is linearized in the step-height, and the steady wavetrain is shown to spread downstream over time. The position of the wavefront is determined by considering the full Stokes structure present in the problem. The equivalent fully-nonlinear problem is then considered, with the position of the Stokes lines, and hence the wavefront, being determined numerically. Finally, linearized three-dimensional free-surface flow past an obstacle is considered in both the steady and unsteady case. The surface is shown to contain downstream longitudinal and transverse waves. These waves are shown to propagate downstream in the unsteady case, with the position of the wavefront again determined by considering the full Stokes structure of the problem.

Ice sheets, such as the Greenland Ice Sheet or Antarctic Ice Sheet, have a fundamental impact on landscape formation, the global climate system, and on sea level rise. The slow, creeping flow of ice can be represented by a non-linear version of the Stokes equations, which treat ice as a non-Newtonian, viscous fluid. Large spatial domains combined with long time spans and complexities such as a non-linear rheology, make ice sheet simulations computationally challenging. The topic of this thesis is the efficiency and error control of large simulations, both in the sense of mathematical modelling and numerical algorithms. In the first part of the thesis, approximative models based on perturbation expansions are studied. Due to a thick boundary layer near the ice surface, some classical assumptions are inaccurate and the higher order model called the Second Order Shallow Ice Approximation (SOSIA) yields large errors. In the second part of the thesis, the Ice Sheet Coupled Approximation Level (ISCAL) method is developed and implemented into the finite element ice sheet model Elmer/Ice. The ISCAL method combines the Shallow Ice Approximation (SIA) and Shelfy Stream Approximation (SSA) with the full Stokes model, such that the Stokes equations are only solved in areas where both the SIA and SSA is inaccurate. Where and when the SIA and SSA is applicable is decided automatically and dynamically based on estimates of the modeling error. The ISCAL method provides a significant speed-up compared to the Stokes model. The third contribution of this thesis is the introduction of Radial Basis Function (RBF) methods in glaciology. Advantages of RBF methods in comparison to finite element methods or finite difference methods are demonstrated. / eSSENCE

The subject of this study is the determination of the resistance of an inland vessel engaged in cargo transport in the lower course of the Magdalena River, considering that the hydrodynamic effects in shallow water navigation are very different compared to the effects in deep water navigation. The hydrodynamic analysis is realized numerically using Computational Fluid Dynamics (CFD). The Reynolds-Averaging Navier-Stokes equation (RANS) solver is applied to simulate viscous and pressure effects around a tank and a hull in confined tank considering the wall bottom and side effects in shallow water navigation. For turbulence effects, realizable k-? model is used. The motion of the vessel causes elevations of the free surface, in which, is captured using the Volume of Fluid method (VOF). For discretization of flow domain, the Finite Volume Method (FVM) is applied. The motion of the fluids is updated for each time step that allows the calculation of the resistance acting on the hull. The numerical simulation results are compared with experimental data obtained by the Technological Research Institute of the State of São Paulo (IPT, acronym in Portuguese) together with the existing empirical methods for this type of cases. / É apresentado um estudo para determinar a resistência de uma barcaça empregada no transporte de carga que poderia operar no setor baixo do rio Magdalena. Os efeitos hidrodinâmicos de um navio em águas rasas são muito diferentes, comparados a esses efeitos em águas com profundidade infinita. A análise hidrodinâmica é realizada numericamente usando a Dinâmica dos Fluidos Computacional (CFD, acrônimo em inglês). A solução das equações de Navier-Stokes (NS) junto com a decomposição do Reynolds (RANS, acrônimo em inglês) é aplicada para simular os efeitos viscosos e de pressão em torno de um tanque e de uma embarcação em um tanque confinado que é caracterizado pelos efeitos do fundo e das paredes. Para efeitos de turbulência, o modelo realizado k-? é usado. O movimento da embarcação do rio provoca elevações da superfície livre que são capturadas usando o método do Volume de Fluido (VOF, acrônimo em inglês). Para a discretização do domínio de fluxo, o Método dos Volumes Finitos (FVM, acrônimo em inglês) é utilizado. O movimento dos fluidos é atualizado para cada intervalo de tempo o que permite o cálculo da resistência atuando no casco. Os resultados da simulação numérica são comparados com dados experimentais obtidos pelo Instituto de Pesquisas Tecnológicas do Estado de São Paulo (IPT), juntamente com os métodos empíricos existentes para esse tipo de casos.

Cette thèse porte sur le développement d’un modèle numérique de l’affouillement causée par des obstacles montes sur le lit, combinant les processus hydrodynamiques et morphologiques. Le modèle numérique est basé sur le solveur de champ d’écoulement polyphasique de l’outil CFD open-source OpenFOAMR qui est distribue par OpenCFD Ltd. Le module hydrodynamique du modèle résout les équations de Navier-Stokes avec moyennes de Reynolds (RANS) et les modèles des turbulences k-ε ou k-ω. Il existe deux interfaces dans le domaine de simulation: la surface libre entre l’eau et l’air, qui est suivi par la méthode de Volume de Fluide (VOF); et l’interface entre l’eau et le lit du sédiment, qui est représentée par un maillage de surface finie déformable construit à partir de la limite en bas du maillage de volume fini. En outre, un module morphologique qui a été développé dans le cadre du projet se compose de trois composantes: un modèle de transport de sédiments comprenant la charge suspendue et le charriage; l’équation d’Exner pour mesurer la déformation du lit; et un mécanisme de glissement du sable pour limiter la pente du lit à être plus petite que l’angle de repos du sédiment. Le changement morphologique est incorporé dans le modèle hydrodynamique par la déformation du maillage. Des conditions limites spéciales et des corrections nécessaires pour le calcul en parallèle sont également ajoutées au modèle. Chaque partie du modèle est validée séparément avec les tests préliminaires correspondants, y compris les fonctions de paroi rugueuse, les performances de la méthode VOF, le modèle de transport de charge suspendu et le mécanisme de glissement de sable. Le modèle numérique est ensuite appliqué pour étudier un affouillent bidimensionnelle cause par un jet immerge provenant d’une ouverture sous écluse. Comparaison des résultats de la simulation avec des données expérimentales prouve la capacité du modèle. Et les limites du modèle sont également discutées. Enfin, le modèle est appliqué à l’étude du champ d’écoulement tridimensionnel et de la formation d’affouillement autour d’un obstacle dans l’écoulement. Tout d’abord, la déformation du lit n’est pas activée. Le tourbillon en fer à cheval devant un obstacle et le champ d’écoulement turbulent autour d’un cylindre sur un lit lisse ou rugueux sont simulés. Deux types de simulation pour le module hydrodynamique sont effectués: une simulation qui utilise une surface fixe et rigide pour représenter l’interface air-eau, et une simulation incluant à la fois les domaines de l’eau et de l’air avec la surface libre suivie par la méthode VOF. Les influences de la surface libre sur le champ d’écoulement sont identifiées et discutées. La comparaison avec les données expérimentales confirme l’importance de la déformation de la surface libre sur le champ d’écoulement. Ensuite, le lit est autorisé à se déformer et le développement temporel de l’affouillement tridimensionnelle autour d’un cylindre sur le lit est simule. Le développement temporel d’affouillement et la profondeur maximale du trou calcule devant et derrière le cylindre conviennent assez bien avec les mesures expérimentales. Les influences de l’affouillement sur le champ d’écoulement sont aussi étudiées et la performance du modèle numérique développé est discutée. / This thesis describes the development of a numerical model for local scour caused by bed-mounted obstacles, combining the hydrodynamic and morphological processes. The basis of the numerical model is the multiphase flow field solver in the open-source CFD toolbox OpenFOAMR which is released by OpenCFD Ltd. The hydrodynamic module of the model solves the Reynolds Averaged Navier-Stokes (RANS) equations with either a k-ε or a k-ω model. There are two interfaces in the simulation domain: the free surface between water and air, which is tracked using the Volume of Fluid (VOF) method, and the interface between the water and the sediment, which is represented by a finite area mesh constructed from the bottom boundary of the finite volume mesh. A morphological module which has been developed as part of the project consists of three components: a sediment transport model which includes suspended load and bed load transport; the Exner equation to compute the bed deformation, and a sand-sliding mechanism to restrict the bed slope angle to be smaller than the angle of repose. The morphological changes are incorporated into the hydrodynamic field through deformation of the computational mesh. Additional boundary conditions and parallel computing corrections are also added into the model. Each individual part of the model has been validated separately with corresponding preliminary test cases including the rough wall functions, the performance of the VOF method, the suspended load transport model and the sand-sliding mechanism. The numerical model is then applied to study two-dimensional scour caused by a submerged jet issuing from an opening under sluice gate. Comparison of the simulation results with the experimental measurements proves the ability of the model for conducting two-dimensional simulations and the limitations of the model are also discussed. Finally, the model is applied to study the three-dimensional flow field and scour formation around an obstacle in flow. Initially, the bed deformation is not activated in the model. The horseshoe vortex formed in front of an obstacle in water and the turbulent flow field around a cylinder on smooth and rough beds are simulated. Two types of simulations for the hydrodynamic module are used: a rigid lid simulation with a slip boundary condition to represent the air-water interface, and a free surface simulation including both the water and air domains with the free surface tracked by the VOF method. The influences of the variation of the water depth on the flow field are identified and discussed. Comparison with the experimental data also confirms the importance of the water surface variation on the flow field. Next, the bed is allowed to deform in the model. The temporal development of three-dimensional scour around a cylinder on live-bed in a steady current is simulated. The development of the scour with time and the computed maximum scour depths in front of and behind the cylinder agree quite well with the experimental measurements. The influences of the scour process on the flow field are also studied and the performance of the numerical model is discussed.

L’écoulement et la stabilité des rideaux liquides viscoélastiques sont étudiés pour des solutions de polymères flexibles et semi rigides. Ces liquides viscoélastiques sont extrudés à partir d’une fente à débit constant et s’écoulent à l’air libre sous l’effet de la gravité. L’écoulement de ces liquides se caractérise par un équilibre initial entre la gravité et les forces élastiques causées par les déformations des chaînes de polymère, jusqu’à ce que l’inertie du liquide finisse par dominer et que l’on retrouve le comportement classique de chute libre. Nous montrons que l’écoulement est principalement influencé par la valeur du temps de relaxation extensionnel mesuré par une méthode de filamentation. Un nouvel éclairage sur l’écoulement des rideaux liquides Newtoniens nous permet de trouver une courbe maîtresse de l’écoulement dans le cas viscoélastique par analogie. En ce qui concerne la stabilité du rideau, nous observons que le débit critique de formation du rideau n’est pas affecté par la présence de polymères, tandis que le débit minimum en deçà duquel le rideau se rompt diminue après ajout de polymères, ce qui révèle une plus grande résistance de la nappe à l’initiation de trous. Par ailleurs, nous observons une instabilité de l’écoulement pour les solutions les plus rhéofluidifiantes, où des bandes épaisses (où la vitesse du liquide est supérieure à la moyenne) sont formées au sein du rideau. Une visualisation de l’écoulement à l’intérieur de la filière d’extrusion révèle que ce phénomène est lié à une instabilité de l’écoulement de contraction en amont de la fente, où l’écoulement est de nature instationnaire et tridimensionnelle. / The flow and the stability of viscoelastic liquid curtains are investigated using solutions of flexible and semi-rigid polymer chains. These viscoelastic liquids are extruded from a slot at constant flow rate and fall in ambient air under gravity. We show that the curtain flow of polymer solutions is characterized by an initial balance between gravity and the elastic stresses arising from the stretching of polymer molecules, until inertia finally dominates and the classical free-fall behavior is recovered. We show that the flow is mostly influenced by the value of the extensional relaxation time of the solution measured by a filament thinning technique. New insights on the theoretical description of Newtonian curtains allow us to find the master curve of the viscoelastic curtain flow by analogy. Concerning the curtain stability, we show that the critical flow rate for curtain formation is not affected by the presence of polymers whereas the minimum flow rate below which the curtain rapidly breaks is reduced by polymer addition, thus revealing a greater resistance of the sheet to hole initiations. Furthermore, we observe the onset of a flow instability for the most shear-thinning solutions, where thick bands (where the liquid velocity is larger than average) are formed within the curtain. Visualizations of the flow inside the die reveal that this phenomenon is linked to a flow instability at the contraction plane upstream of the slot where the flow is unsteady and three-dimensional in nature

<p>This thesis describes a system for dealing with free surface fluid simulations, and the components needed in order to construct such a system. It builds upon recent research, but in a computer graphics context the amount of available literature is limited and difficult to implement. Because of this, the text aims at providing a solid foundation of the mathematics needed, at explaining in greater detail the steps needed to solve the problem, and lastly at improving some aspects of the animation process as it has been described in earlier works. </p><p>The aim of the system itself is to provide visually plausible renditions of animated fluids in three dimensions in a manner that allows it to be usable in a visual effects production context. </p><p>The novel features described include a generalized interaction layer providing greater control to artists, a new way of dealing with moving objects that interact with the fluid and a method for adding source and drain capabilities.</p>

A computational model is developed to investigate fundamental flow physics and transport phenomena of evaporating wavy-laminar falling liquid films of water and black liquor. The computational model is formulated from first principles based on the conservation laws for mass, momentum, energy and species in addition to a phase transport equation for capturing interface deformation and evolution. Free surface waves are generated by monochromatic perturbation of velocity. Continuum models for interfacial evaporation define source terms for liquid vaporization and species enrichment in the conservation laws. A phenomenological crystallization model is derived to account for species depletion due to salt precipitation during black liquor falling film evaporation. Using highly resolved numerical grids on parallel computers, the computational model is implemented to analyze the dynamics of capillary separation eddies in low Reynolds number falling films, investigate the dominant mechanisms of heat transfer enhancement in falling films at moderately high Reynolds numbers and study the fundamental wave structures and wave induced transport in black liquor falling films on flat and cylindrical walls. From simulation results, a theory based on the dynamics of wavefront streamwise pressure gradient is proposed to explain interfacial waves interaction that give rise to multiple backflow regions in films dominated by solitary-capillary waves. The study shows that the mechanism of heat transfer enhancement in moderately high Reynolds number films follows from relatively lower conduction thermal resistance and higher crosswise convective transport at newly formed intermediate wavefronts. Interfacial phenomena such as wave-breaking and vapor entrainment observed in black liquor falling films is explained in terms of a mechanistic theory based on evolution of secondary instabilities and large amplitude wave force imbalances.

Στην παρούσα εργασία μελετάται αριθμητικά η ροή σε σήραγγα υπό συνθήκες ελεύθερης επιφάνειας και έντονης κλίσης πυθμένα 1:10. Διερευνάται η δυνατότητα μείωσης της ταχύτητας ροής μέσω κατακόρυφων, πλευρικών στοιχείων τραχύτητας. Συγκεκριμένα γίνεται τρισδιάστατη προσομοίωση της ροής με χρήση του μοντέλου ANSYS – Fluent και τα αποτελέσματα συγκρίνονται με εκείνα που προέκυψαν από αντίστοιχο πείραμα που πραγματοποιήθηκε στο Εργαστήριο Υδραυλικής Μηχανικής του Τμήματος Πολιτικών Μηχανικών του Πανεπιστημίου Πατρών. Αφορμή για το συγκεκριμένο σχεδιασμό αποτέλεσε η διερεύνηση της εκτροπής των πλημμυρικών παροχών από ορεινή λεκάνη σε κατάντη ταμιευτήρα μέσω σήραγγας και συγκεκριμένα από το οροπέδιο Λασιθίου στον ταμιευτήρα του φράγματος Αποσελεμή. Με δεδομένα τα ανωτέρω, επιθυμείται να αποφευχθεί η κατασκευή βαθμίδων ή στοιχείων τραχύτητας στον πυθμένα και, επομένως, απαιτείται η μόρφωση «πτυχώσεων» στα τοιχώματα έτσι ώστε να αναπτυχθεί δευτερογενής ροή και με εισρόφηση αέρα. Η αποτελεσματικότητα του σχεδιασμού διερευνήθηκε σε υδραυλικό ομοίωμα κλίμακας 1:12.5 που βασίσθηκε σε συνθήκες δυναμικής ομοιότητας κατά Froude για χαρακτηριστικές τιμές παροχής. Η επεξεργασία των μετρήσεων έδειξε ότι με κατάλληλη διάταξη πλευρικών στοιχείων τραχύτητας ελέγχεται η τιμή της ταχύτητας και ικανοποιείται η απαίτηση μεγίστου βάθους ροής σε σχέση με τις διαστάσεις της σήραγγας. Για την υπολογιστική επίλυση του προβλήματος αξιοποιήθηκαν οι εξισώσεις Reynolds-Averaged Navier-Stokes (RANS), ενώ για το κλείσιμο της τύρβης χρησιμοποιήθηκε το μοντέλο δυο εξισώσεων k-ω, το οποίο επεξηγείται αναλυτικά. Η διαχείριση της ελεύθερης επιφάνειας έγινε με τη μέθοδο Volume of Fluid (VOF), ενώ η αριθμητική επίλυση βασίστηκε στη μέθοδο των πεπερασμένων όγκων και πραγματοποιήθηκε με το υπολογιστικό πακέτο Fluent CFD της ANSYS inc. Για την ροή στον υπό εξέταση αγωγό η ροή είναι υπερκρίσιμη με κλίση πυθμένα S_0=0.10. Για λόγους ελέγχου της ακρίβειας της αριθμητικής μεθόδου που χρησιμοποιήθηκε, αρχικά επιλύθηκε η περίπτωση τρισδιάστατου καναλιού ορθογωνικής διατομής χωρίς πλευρικά στοιχεία τραχύτητας και τα αποτελέσματα που προέκυψαν συγκρίθηκαν με αναλυτικά αποτελέσματα μονοδιάστατης ροής (κατακόρυφο επίπεδο) υπεράνω επίπεδου πυθμένα. Τα αποτελέσματα βρέθηκαν σε καλή συμφωνία μεταξύ τους, γεγονός που επιβεβαίωσε την καταλληλότητα της μεθόδου. Για το τρισδιάστατο πρόβλημα με τα κατακόρυφα πλευρικά στοιχεία τραχύτητας, η ανάλυση έδειξε ότι το διάμηκες προφίλ της ελεύθερης επιφάνειας παρουσιάζει κυματισμούς σε όλη την περιοχή των στοιχείων τραχύτητας. Το βάθος ροής κατέρχεται σταδιακά από το αρχικό κρίσιμο βάθος μέχρι να φθάσει στο επίπεδο του βάθους των 0.06 m, το οποίο δεν είναι το ομοιόμορφο βάθος αφού η ροή συνεχίζει να επιταχύνεται. Επιπροσθέτως, παρατηρήθηκε η δημιουργία μιας περιοχής ανακυκλοφορίας της ροής ανάμεσα στα πλευρικά στοιχεία τραχύτητας. Τα αποτελέσματα που πρόεκυψαν από το αριθμητικό μοντέλο συγκρίθηκαν με τα πειραματικά αποτελέσματα και η συμφωνία μεταξύ αριθμητικών προβλέψεων και πειραματικών δεδομένων είναι ιδιαίτερα ικανοποιητική. / A three-dimensional CFD numerical model has been utilized to simulate the 3D free-surface flow under supercritical flow conditions in a 10% sloping channel over vertical roughness elements on the side walls. The effectiveness of vertical roughness elements on the side walls is investigated, with the aim to reduce flow velocity in the tunnel. The program, ANSYS Fluent, solves the Reynolds-Averaged Navier-Stokes (RANS) equations on an unstructured five-hedral grid using PISO method and the flow is treated as steady while the k-omega model is used as turbulence model. The numerical simulation has been based on the Volume of Fluid method (VOF) approach. Available experimental measurements of the free-surface in a sloping channel, under various supercritical flow regimes, have been used to validate the proposal numerical methodology. These experiments were conducted at the Hydraulic Engineering Laboratory of the Civil Engineering Department, University of Patras. In all test cases the 3D numerical model gives reasonable comparisons with measurements for the water depth.