Unsteady Reynolds-Averaged Navier-Stokes Solver Research Articles

Numerical simulations of cavitating water jet by an improved cavitation model of compressible mixture flow with an emphasis on phase change effects

Focusing on cavitation phenomena caused by high-speed submerged water jets, this paper presents an improved cavitation model for a compressible fluid mixture based on a concise estimation of fluid compressibility that considers phase change effects. The homogeneous two-phase flow assumption is adopted, and the gas phase is assumed to consist of vapor and non-condensable components. Equations of state for a pure liquid and an ideal gas are employed to evaluate the compressibility of the liquid and non-condensable components, and the compressibility of the vapor is treated semi-empirically as a constant. The model is embedded in an unsteady Reynolds-averaged Navier–Stokes solver, with the realizable k-ε model employed to evaluate the eddy viscosity. The turbulent cavitating flow caused by an impulsively started submerged water jet is treated. The pattern of periodic cavitation cloud shedding is acceptably captured, and the mass flow rate coefficient and its fluctuation frequency evaluated by simulations agree with the experimental results well. The validity of the proposed method is confirmed. The results reveal that cavitation occurs when pin/Pin reaches 0.65 and fluid flow begins to pulsate. In the well-developed stage, the leading cavitation cloud and a subsequent cloud are successively shed downstream, and this process is repeated. The subsequent cloud catches the leading cloud, and they coalesce in the range x/d≈ 2–3. The pressure fluctuations concentrate in the range of x/d≈2–5 corresponding to the periodic shedding of cavitation clouds. The mass flow rate coefficient pulsates from 0.59–0.66 under the effect of cavitation.

Numerical study of periodic flame flashback in a cavity-based scramjet combustor

The periodic flame flashback phenomenon in an ethylene-fueled cavity-based scramjet combustor was numerically investigated by a three-dimensional unsteady Reynolds-averaged Navier–Stokes solver with two-step kinetics. The air inflow stagnation temperature is 1225 K, and its Mach number is 2.6. Spectral analyses revealed the combustion oscillations with flame flashbacks maintained in the separated scramjet mode with the establishment/vanishment of flow separation near the fuel injector, differing from previous studies of flame flashbacks connected to the ramjet/scramjet mode transitions. A mechanism with four evolution stages was proposed to elucidate the flow-flame interaction. In stage I, a rapid flame flashback upstream and shock-train extension were caused by the high-temperature induced auto-ignition tendency of well-mixed unburned gas in the near-sidewall low-speed region. In stage II, the combustion-induced back pressure and shock train gradually achieved an aerodynamic balance. The combustion flow barely changed in stage III. Meanwhile, a simplified model suggested that the gradual temperature rises occurring upstream of the cavity and away from the sidewall were caused by spanwise heat conduction. The higher temperatures would cause upstream flame propagation with enhanced heat release due to auto-ignition. However, the enhanced heat release occurred mostly in the subsonic flow, resulting in pressure decreases according to one-dimensional flow equations. A smaller near-sidewall separation was produced by the lower back-pressures, which prompted the rapid flame recession downstream in stage IV. Moreover, a simplified flame-spreading model was proposed to illuminate the flame propagation nature. The comparison of flame speeds with theoretical estimations indicated that the current flame was in the regime of turbulent flame propagation, rather than the C–J detonation or deflagration speculated in previous studies.

Nonlinear URANS model for path-following control problem towards autonomous marine navigation under wave conditions

An accurate prediction of the performance of maritime autonomous surface ships (MASS) to follow a predefined path in waves is of critical importance for ensuring safe autonomous marine navigation. Traditional methods for the study of path-following problems are based on simplified mathematical ship models and are incapable of precisely resolving the complicated interactions between the hull, propeller, rudder, and incident waves under path-following control. In the present study, a CFD-based dynamic model for path-following problems is developed for autonomous marine navigation by means of a fully nonlinear unsteady Reynolds-Averaged Navier-Stokes (RANS) solver combined with the Line-of-Sight (LOS) guidance law. Fortunately, an unsteady RANS solver is capable of incorporating viscous and turbulent effects and the free surface resolution critical to path-following problems, allowing a better prediction of a ship's path-following performance in waves. To obtain practical insight into the performance of the ship executing path-following control for autonomous navigation in waves, a comprehensive analysis of path-following tasks in waves covering the whole range of important wave directions and wave heights was carried out in this study. The numerical results demonstrated that when the ship performed the path-following manoeuvre under the beam and quartering seas, the greatest oscillatory deviation from the predefined path was observed due to the asymmetric pressure distribution on the ship hull caused by the incident waves. It was also confirmed that wave heights strongly affected the trajectories experienced by the ship performing the path-following task in the beam and oblique seas; the deviation from the predefined path was found to increase with the increase in the wave height. As high-performance computational resources become increasingly available, the proposed CFD method will provide an accurate and efficient way to predict the performance of autonomous surface ships performing path-following tasks in waves, providing a valuable contribution to enhancing the safety of autonomous marine navigation.

Hydrodynamic interaction study during surface ship overtaking submarine

Submarine is easily disturbed by the passing surface ships when submarine sailing near the sea surface, the disturbance can greatly affect the hydrodynamic performance and sailing status of the submarine during navigation. In this study, A model-scale tanker (KVLCC2,LPP = 32m) and a model-scale submarine (SUBOFF,Loa = 6.534m) were used to study the hydrodynamic interaction to the submarine when the surface ship overtakes the submarine sailing below it. An in-house unsteady Reynolds-averaged Navier–Stokes solver was applied to the simulation. First, uncertainty analysis of the computational fluid dynamics (CFD) solver was conducted, and validation study based on available experimental data showed good agreement. The hydrodynamic interaction to the submarine during the overtaking process was then investigated numerically with different submarine forward speed, tanker forward speed and different tanker-submarine vertical distance. The results showed that the vertical distance between tanker and submarine has great influence on submarine, the peak values of vertical force and pitching moment of submarine were obviously affected by the forward speed of tanker and submarine, meanwhile, The interaction force on submarine resistance was less effected by submarine forward speed, but the forward speed of tanker was more effected.

A systematic investigation on the manoeuvring performance of a ship performing low-speed manoeuvres in adverse weather conditions using CFD

The International Maritime Organisation (IMO) requirements for the control of greenhouse gas (GHG) emissions of shipping have raised interest in ship manoeuvrability in adverse weather conditions when compliance is accomplished simply by reducing the main engine power. In response, the IMO has adopted the guidelines for determining minimum propulsion power to maintain the manoeuvrability of ships in adverse conditions. In the present paper, a systematic investigation on the manoeuvrability of a ship with different low advance speeds in adverse weather conditions was conducted by means of an unsteady Reynolds-Averaged Navier-Stokes solver. The numerical results demonstrated the contribution of low advance speeds to the course-keeping and turning circle manoeuvre, providing a practical insight into the manoeuvring performance of a ship with minimum propulsion power in adverse weather conditions. For the course-keeping control, the ship experienced more aggressive steering as the propeller revolution decreased in the oblique waves, while it appeared that the difference in the rudder deflection according to the change in the propeller speed in the head, beam, and following waves is negligible. The difficulty of the low speed turning manoeuvre was clearly noted when the direction of the incident wave was opposite to the direction towards which the ship intended to turn. It is believed that this paper can also be impactful in improving the guidelines of minimum powering of ships for safe navigation in adverse weather conditions.

A study on ship performance in waves using a RANS solver, part 2: Comparison of added resistance performance in various regular and irregular waves

Commercial ships frequently operate under irregular sea conditions; hence, their performance must be estimated through simulations in a more realistic environment. To date, a number of experiments and numerical studies have been conducted using regular waves to estimate added resistance. In this study, the performance of the KVLCC2 hull considering the added resistance in various regular and irregular waves was evaluated using an unsteady Reynolds-averaged Navier–Stokes solver. Resistance and motion responses were observed for regular waves with various wavelengths, regular waves with various wave steepness, and bichromatic waves superposed with regular waves. The change in resistance performance and damping with respect to motion response based on wave height was analyzed. An irregular wave corresponding to the joint North Sea wave project spectrum under sea state 6 was derived; based on this derived wave, the added resistance in irregular waves was estimated. The added resistance was compared with the estimated value using the spectral method, which was also employed to derive the added resistance under the target sea state using regular wave results. The estimated values differ from the direct calculation results owing to the nonlinearity of resistance in the irregular wave. However, the motion responses showed a similar tendency to those of the regular wave (except for those in the proximity of natural frequency that were relatively large and could be influenced by the wave height), as observed when various wave steepness values were used.

Numerical Investigation of Contact Burning in an Air-Breathing Continuous Rotating Detonation Engine

Three-dimensional (3D) numerical simulations of a continuous rotating detonation engine are carried out with an unsteady Reynolds-averaged Navier-Stokes solver. The second-order upwind advection upstream splitting method and second-order Runge-Kutta method are used to discretize space and time terms, and detailed 9-species 19-step hydrogen-oxygen reactions are applied in this study. Nonpremixed rotating detonation is successfully realized numerically, and the characteristics of the detonation wave are revealed. The expanding angle of the combustor has a great impact on the shape of the detonation wave but has little influence on the propagation velocity. The evolution of combustion on the contact region is analyzed in detail; a more accurate schematic of non-premixed air-breathing rotating detonation engines is given in this paper. A rough analysis of the heat performance of the contact region shows that the heat release of the contact region is approximately one-third of the total heat release and the configurations of the combustors do not affect the proportion.

Numerical study of swell impact on seakeeping performance of surface combatant

The complex sea states with the co-occurrence of swell and wind-sea conditions represent threats to sailing vessels. This study presents the computational fluid dynamics (CFD) simulations for a surface combatant model advancing in mixed seas combined with the swell and wind-sea components, aimed at estimating the swell impact on ship seakeeping performance. An in-house unsteady Reynolds-averaged Navier–Stokes solver coupled with an overset grid approach is applied to the numerical predictions, along with the assessment study for the model advancing in calm water and harmonic wave group based on the existed model tests, indicating the CFD results agree well with the experimental data. Irregular wave simulations are then conducted for the model advancing in head seas combined with different swell and wind-sea components. Comparisons of ship seakeeping behaviors for wind-sea dominated, energy equivalent, and swell dominated mixed seas are carried out with the statistical assessment and frequency analysis. Overall, both the heave and pitch amplitudes are larger as the ship is advancing in swell dominated sea than those in the other two seas. The ship motions are also predicted in wind sea and it indicates that the ship encounters the larger heave motion in mixed seas compared with that in wind sea.

Numerical study on the effect of sloshing on ship parametric roll

In this study, numerical simulations of the parametric roll of a ship coupled with liquid sloshing were performed. A model-scale ONR Tumblehome was used for the simulation, and the ship was equipped with a partially filled liquid tank. An in-house unsteady Reynolds-averaged Navier–Stokes solver was applied to the numerical simulation of the coupling effect between the sloshing and parametric roll of the ship in regular head waves. First, a validation study of the computational fluid dynamics (CFD) solver was conducted. Comparisons between the CFD and experimental results showed good agreement. Systematic grid and time-step convergence studies were performed to estimate the numerical uncertainty. The effect of liquid sloshing on the parametric roll of a ship was then investigated numerically with different liquid levels and different ship forward speeds. The results demonstrated that water sloshing could significantly decrease the natural roll frequency of the ship model, which led to a lower speed range where the parametric roll occurred compared with the model without sloshing. The phase difference between the total moment and sloshing-induced moment was close to 180°, resulting in a reduction of the parametric roll amplitude. Sloshing had slight effects on the amplitudes of the heave and pitch motions.

Hydrodynamic analysis of three oscillating hydrofoils with wing-in-ground effect on power extraction performance

Currently, oscillating-foil power extraction turbines have been developed as a new competitive way compared with rotor blade designs. In the present study, oscillating hydrofoils with a heaving amplitude of one chord at the Reynolds number of Re = 500,000 are employed in a fully prescribed motion to investigate the wing-in-ground (WIG) effect on the power extraction performance. To prescribe the heaving and pitching motions, the harmonic sinusoidal function is actively imposed. An unsteady Reynolds Averaged Navier-Stokes solver based on an open-source CFD code OpenFOAM is used to solve this problem. The fields of the pressure and velocity around a foil are analyzed when the foil approaching and departing from the ground. According to the distribution of pressure on the upper and lower surfaces of the foil, it is found that the efficiency of the power extraction increases mainly due to the increment of the positive pressure on the lower surface. The maximal improvement of the power-extraction efficiency is 7.36% when the minimum gap is 0.25 chord length. A parametric study with different gaps is conducted to predict the optimal power-extraction region. The optimal power-extraction zone shifts to the higher frequency as the gap decreases. The maximal efficiency of the power extraction reaches 41.67%. The wing-in-ground effect turbine (WIGT) by multi-hydrofoils is also simulated and it has a satisfying consequence with the increment of the power-extraction efficiency of 13.37% of the middle hydrofoil which experiences twice the WIG effect.

Three-dimensional propulsion characteristics of counter-phase oscillating dual-foil propulsor

A three-dimensional computational study was conducted on the propulsive performance of auto-pitch wing-in-ground effect oscillating foil propulsors (APWIGs) using an unsteady Reynolds Averaged Navier-Stokes solver. This novel propulsor is characterized as the combination of dual-foil configuration and spring-based pitching motion. Both the counter-phase oscillating dual-foil arrangement with produced wing-in-ground (WIG) effect and the auto-pitch mechanism based on attached torsional springs are expected to be favorable for performance improvement. To clearly identify the role of two concerned parameters for APWIGs, the study was divided into two parts of simulations to examine aspect ratio and torsional spring stiffness separately. Firstly, the effect of aspect ratio on the hydrodynamic characteristics was investigated by a fully prescribed oscillating dual-foil configuration. The current computations covering a wide range of aspect ratio from 1 to 10 indicated that the three-dimensional effect tends to dominate the propulsion hydrodynamics with a value of lower than 2. The maximum drop of 14.85% in propulsive efficiency due to the finite-span effect was found at the aspect ratio of 1, while a moderate aspect ratio of 4 leads to an acceptable efficiency loss of 3.22%. Secondly, the three-dimensional hydro-elasticity characteristics of APWIGs as a function of spring stiffness were studied by employing a fixed aspect ratio. A relatively low aspect ratio in which the finite-span effect is still dominant was selected to compare the three-dimensional simulations with two-dimensional predictions. It was observed that the torsional spring stiffness has a significant influence on both hydrodynamic performance and vortex structures of finite-span APWIGs. There exists an optimum spring stiffness for finite-span APWIGs corresponding to the highest efficiency, which resembles the hydro-elasticity characteristics of two-dimensional cases. An averaged efficiency loss of around 10% was reported owing to the low-aspect-ratio effect for three-dimensional APWIGs.

Coupled Aeroelastic Study of a Flexible Micro Air Vehicle-Scale Flapping Wing in Hovering Flight

Instantaneous force and structural deformation experiments were performed on a flexible, structurally characterized, low-aspect-ratio representative flapping wing. A six-component force balance was used to measure aerodynamic-force time history over a flap cycle. A VICON motion capture setup tracked the wing deformations while flapping. Measured aerodynamic forces and wing deformations were compared against coupled computational fluid dynamics/computational structural dynamics (CFD/CSD) aeroelastic analysis results. The CFD solver is an unsteady Reynolds-averaged Navier–Stokes solver. The CSD solver is a general-purpose multibody dynamics solver capable of modeling geometrically nonlinear beam and shell elements. The CFD/CSD results were able to capture the overall trend in aerodynamic forces and wing deformations. Although predicted and measured variations in lift were similar, the drag-force magnitudes tended to be underpredicted by the coupled aeroelastic solver. The coupled CFD/CSD solver was used to evaluate the influence of wing flexibility on wing performance. Results showed that, in particular instances, decreasing wing stiffness increased the time-averaged aerodynamic lift and lift-to-power ratio. Decreased wing stiffness led to reduced leading-edge vortex circulation strength. This suggests that the increased wing performance is mainly due to a redirection of the resultant force vector allowed by the increased wing compliance.

Prediction of the acceleration and stopping manoeuvres of a bare hull surface combatant by closed-form solutions and CFD

In this study, the acceleration and stopping manoeuvres of a bare hull surface combatant have practically been predicted by closed-form (analytical) solutions derived from basic mechanical principles. They have also been simulated directly by an unsteady RANS (Reynolds-averaged Navier-Stokes) solver with overset grid structure to compare the results with those of closed-form approaches. A well-known surface combatant model DTMB5415 has been chosen for validation. The instantaneous drag forces of the model ship in the acceleration and stopping manoeuvres have been provided by both CFD and Holtrop's methods. It has been observed that the results by analytical solutions have a good match with those of the manoeuvring simulations based on unsteady RANS solver. Successful predictions have also been made consistent with the results obtained when experimental resistance values are used in analytical solutions. It has been concluded that the closed-form solution methods yield practically satisfactory results in a very short time when a fast resistance prediction method, such as Holtrop's method or CFD, is used.

Thermal power plant upgrade via a rotating detonation combustor and retrofitted turbine with optimized endwalls

In the past decade, pressure gain combustion research has promised over 10 percentage-points of increase in power plant thermal efficiency. Alas, to realize such potential gain, one must effectively couple the turbine with the detonation combustor, whose exhaust conditions differ substantially from current state of the art gas turbines. This paper presents a modeling approach that enables a superior thermodynamic cycle with a rotating detonation combustor and a retrofitted gas turbine by including a diffuser downstream of the combustor and by contouring the turbine endwall, while preserving the airfoil geometry. We propose a multi-step optimization strategy, parametrizing the endwall geometry with a few control points, without altering the airfoil geometry, and with the stage turbine efficiency as objective function. In a first step the turbine performance is assessed with steady inlet conditions by solving the steady three-dimensional Reynolds-Averaged Navier-Stokes equations. In a second step, the inlet conditions are unsteady, as predicted from a detonation combustor and a diffuser, and three-dimensional full unsteady simulations are performed with an unsteady Reynolds-Averaged Navier-Stokes solver. By altering the vane endwall, the steady optimization yielded an efficiency increase of 12% relative to the baseline, while the unsteady optimization resulted in 21% increase compared to the datum turbine. Finally, a full engine analysis demonstrated the superiority of pressure gain combustion which included a realistic thermodynamic cycle of the combustor, the diffuser and the optimized turbine components.

Parametric study on hydro-elasticity characteristics of auto-pitch wing-in-ground effect oscillating foil propulsors

A parametric study on the propulsive performance of auto-pitch wing-in-ground effect oscillating foil propulsors (APWIGs) was conducted using an unsteady Reynolds Averaged Navier-Stokes solver. The harmonic sinusoidal function is actively imposed to the heave motion of such a configuration, which has a passively flow-induced pitch motion restrained by torsional springs. Comparative investigation between APWIGs and fully prescribed system was performed, indicating that APWIGs is capable of producing a satisfactory propulsive efficiency within a wide range of advance speed. The jet-like profiles implying the time-averaged momentum surplus were obtained in the wake of APWIGs, which is attributed to the produced reverse Kármán vortex street behind each oscillating foil. Obvious vortex shedding along both leading edge and trailing edge can be observed at a high reduced frequency, while the low oscillating frequency corresponding to a small reduced frequency tends to produce the high efficiency due to the highly attached flow around foil surface. Furthermore, comprehensive computations for the influence of multiple parameters on the hydro-elasticity responses and propulsive characteristics of APWIGs were conducted in the current study. We noted that heaving amplitude and equilibrium distance only affect the maximum flow-induced pitching angle. Nonetheless, the position of elastic pitching axis shows a significant effect on both pitch-leading phase difference and the maximum pitching angle. The maximum increase of propulsive efficiency around 12% due to the wing-in-ground effect was discovered within the considered parametric space. It was found that the APWIGs can achieve a high efficiency of over 70%, with the appropriate combination of geometry and motion parameters.

Numerical investigation of auto-pitch wing-in-ground effect oscillating foil propulsor

The propulsive characteristics of auto-pitch wing-in-ground effect oscillating foil propulsors (APWIGs) were numerically investigated through an unsteady Reynolds Averaged Navier-Stokes solver. The kinematics of such a biplane configuration is characterized by the prescribed heave motion and flow-induced pitch motion restrained by a torsional spring for each foil. Based on the validated numerical model, the comparison of propulsive performance between APWIGs and single auto-pitch oscillating foil, as well as dual-foil heave-only configuration, was conducted at different advance speeds. Results show that APWIGs is advantageous in both thrust production and efficiency enhancement over other two configurations due to the resulting wing-in-ground effect and substantial reduction of flow separation by the flow-regulated pitch motion. Furthermore, the effect of torsional spring stiffness on the propulsion of APWIGs was studied under different loaded conditions. It was found that both the maximum pitching angle and phase difference of pitch with heave are dramatically affected by the spring stiffness, which has major contribution to the hydrodynamic behaviours of the foils. Under a certain operating speed, an optimal torsional spring stiffness that produces the best propulsive performance can be found. With respect to the parametric space in the current study, the APWIGs can achieve a constant high efficiency over 70% by employing an appropriate spring stiffness.

Performance improvement of helicopter rotors through blade redesigning

Purpose The purpose of this paper is to determine dependencies between a rotor-blade shape and a rotor performance as well as to search for optimal shapes of blades dedicated for helicopter main and tail rotors. Design/methodology/approach The research is conducted based on computational methodology, using the parametric-design approach. The developed parametric model takes into account several typical blade-shape parameters. The rotor aerodynamic characteristics are evaluated using the unsteady Reynolds-averaged Navier–Stokes solver. Flow effects caused by rotating blades are modelled based on both simplified approach and truly 3D simulations. Findings The computational studies have shown that the helicopter-rotor performance may be significantly improved even through relatively simple aerodynamic redesigning of its blades. The research results confirm high potential of the developed methodology of rotor-blade optimisation. Developed families of helicopter-rotor-blade airfoils are competitive compared to the best airfoils cited in literature. The finally designed rotors, compared to the baselines, for the same driving power, are characterised by 5 and 32% higher thrust, in case of main and tail rotor, respectively. Practical implications The developed and implemented methodology of parametric design and optimisation of helicopter-rotor blades may be used in future studies on performance improvement of rotorcraft rotors. Some of presented results concern the redesigning of main and tail rotors of existing helicopters. These results may be used directly in modernisation processes of these helicopters. Originality/value The presented study is original in relation to the developed methodology of optimisation of helicopter-rotor blades, families of modern helicopter airfoils and innovative solutions in rotor-blade-design area.

Parametric study on the aeroelastic stability of rotor seals

Labyrinth seals are widely used in rotating machinery and can be prone to aeroelastic instabilities. The rapid development of computational fluid dynamics now provides a high-fidelity approach for predicting the aeroelastic behavior of labyrinth seals in three dimension and exhibits great potential within industrial application, especially during the detailed design stages. In the current publication a time-marching unsteady Reynolds-averaged Navier-Stokes solver was employed to study the various historically identified parameters that have essential influence on the stability of labyrinth seals. The findings from the numerical approach agree well with analytical criteria in determining the overall stability of the seal structure while being able to capture the acoustic behavior of the upstream or downstream large cavities and its influence on the inter-fin cavities. The high-fidelity approach provides additional insights on the effects of nodal diameter, travelling wave direction, pressure ratio, and the linearity of the phenomenon for relatively large vibration amplitudes, all of which can aid during the design space exploration.

On the Applicability of Cavitation Erosion Risk Models With a URANS Solver

In the maritime industry, cavitation erosion prediction becomes more and more critical, as the requirements for more efficient propellers increase. Model testing is yet the most typical way a propeller designer can, nowadays, get an estimation of the erosion risk on the propeller blades. However, cavitation erosion prediction using computational fluid dynamics (CFD) can possibly provide more information than a model test. In the present work, we review erosion risk models that can be used in conjunction with a multiphase unsteady Reynolds‐averaged Navier–Stokes (URANS) solver. Three different approaches have been evaluated, and we conclude that the energy balance approach, where it is assumed that the potential energy contained in a vapor structure is proportional to the volume of the structure, and the pressure difference between the surrounding pressure and the pressure within the structure, provides the best framework for erosion risk assessment. Based on this framework, the model used in this study is tested on the Delft Twist 11 hydrofoil, using a URANS method, and is validated against experimental observations. The predicted impact distribution agrees well with the damage pattern obtained from paint test. The model shows great potential for future use. Nevertheless, it should further be validated against full scale data, followed by an extended investigation on the effect of the driving pressure that leads to the collapse.

Vertical Water Entry of a Flexible Wedge into Calm Water: A Fluid-Structure Interaction Experiment

Slamming water impact occurs frequently on high-speed craft and restricts the operating envelope of a vessel. One approach to understanding the hydroelastic nature of this phenomenon is to study the vertical impact of a V-shaped wedge on calm water, which models a single slamming event after a vessel has become partially airborne. The dynamic structural response of the bottom plate of a wedge dropped vertically (drop height = 7.9 cm) is investigated both experimentally and computationally. The experiments were conducted with a flexible bottom model at Virginia Tech. Pressure on the wedge bottom, rigid body motion (vertical acceleration and vertical position), and full-field out-of-plane deflection were measured. The out-of-plane deflection was measured using stereoscopic digital image correlation. Predictions on the hydrodynamic pressure field were made using Wagner's method, Vorus's method, and an unsteady Reynolds-averaged Navier-Stokes solver, all assuming a rigid plate. In the present work, the reconstructed pressure distribution from the experiment was used as the loading condition in a dynamic, linear finite element plate model (one-way coupled approach). Both the predicted pressure and predicted deflection were compared with the experiment. It was found that in the experiment, there is a slight reduction in the measured hydrodynamic pressure compared with predictions. This reduction in pressure leads to a reduction in the reactions at the plate edges, which get transmitted to the frames of the vessel. This slight reduction at small loading cases has the potential to be more noticeable when more severe slamming loads are encountered. 1. Introduction Slamming water impacts occur when a vessel impacts the water surface at high speed relative to the free surface. Water impact was first studied by von Karman (1929) with the application of seaplane landing. Water impact, as it pertains to slamming, gradually attracted increasing attention in the application of high-speed craft. The understanding of this phenomenon has been applied to the structural design and evaluation of the operational envelope of high-speed planing craft. Sailors also consider slamming a serious risk because it contributes to major injuries in addition to mission-related setbacks such as speed reduction or heading change. The present investigation of slamming can lead to the development of better design criteria for small craft.