Inertia Coefficients Research Articles

Identification of Parameters and States in PMSMs

This paper discusses the importance of accurately identifying the parameters and states in permanent magnet synchronous motors (PMSMs) and their impact on motor performance and efficiency. This study was conducted to demonstrate the significance of these parameters. The results showed that inaccurate identification of the friction coefficient and moment of inertia led to poor motor performance, instability, and reduced efficiency. Accurate identification of these parameters is necessary for the proper control and operation of PMSMs. This paper highlights the various methods for calculating the friction coefficient and moment of inertia, as well as their potential limitations. The findings of this study emphasize the importance of accurately identifying these parameters for the efficient and effective operation of PMSMs.

Adaptive Droop Control of VSC-MTDC System Based on Virtual Inertia

In order to solve the problem that the voltage source converter based multi-terminal direct current (VSC-MTDC) system cannot provide inertia and participate in frequency modulation after connecting to the AC power grid under the traditional control strategy, an adaptive control strategy based on virtual inertia is proposed. First, the relationship between AC frequency and DC voltage was established by a virtual inertia control, allowing the VSC-MTDC system to provide inertia to the AC side. Second, to address the limited inertia coefficient selection due to DC voltage deviation, an adaptive control was adopted. When the DC voltage deviation is small, the inertia coefficient is increased to obtain a better inertial response; on the contrary, the inertia coefficient is reduced to prevent the DC voltage from exceeding the limit. Finally, to solve the problem of insufficient flexibility of the fixed droop coefficient, this paper introduces the power margin of a VSC-station into the droop coefficient to dynamically adjust the distribution ratio of unbalanced power and reduce the DC voltage deviation. The three-terminal VSC-MTDC system was modelled on the PSCAD/EMTDC simulation platform, and the superiority of the control strategy was highlighted in this paper by comparing it with conventional droop control and a fixed virtual inertia coefficient.

Functional magnetic Maxwell viscoelastic nanofluids for tribological coatings- a model for stretching flow using the generalized theory of heat-mass fluxes, Darcy-Forchheimer formulation and dual convection

A theoretical and computational study of an improved Fourier and Fickian model for locally non-similar magnetohydrodynamic Maxwell (non-Newtonian) nanofluid convective flow under thermo-solutal buoyancy forces in a non-Darcian (Darcy-Forchheimer) porous medium is presented. Heat sink/source is included. Buongiorno’s two-component nanofluid model is used to simulate nanoscale characteristics featuring thermophoresis and Brownian diffusions. The problem under consideration is formulated utilizing fundamental relations of fluid dynamics. The primitive partial differential expressions (PDEs) are transfigured to ordinary ones with apposite transformations. The emerging locally non-similar boundary value problem is solved via series expansions utilizing a homotopy algorithm. Characteristics of sundry parameters on velocity, temperature, nanoparticle concentration and skin-friction coefficients are interpreted graphically. Convergence results acquired via homotopy algorithm are presented. Comparison results are included for the authentication of the homotopy solutions. The velocity distribution is increased with greater mixed convection and non-Newtonian material parameters whereas velocity distribution is reduced with increment in Hartmann (magnetic) number, porosity and buoyancy ratio parameters. The temperature distribution is reduced when Prandtl number and thermal-relaxation (non-Fourier) parameter are augmented whereas temperature distribution is increased for larger Brownian diffusion and thermophoresis. Additionally, it is observed that increment in the heat absorption variable diminishes temperature whereas an enhancement in the heat generation variable augments temperature. Nanoparticle concentration is enhanced subjected to higher values of thermophoresis factor whereas it reduces with larger Schmidt number, Brownian movement and solutal-relaxation (non-Fickian) parameters. Furthermore, it is noticed that elevation in Hartmann number, porosity and inertial (non-Darcy) coefficient parameters increase the skin friction coefficient whereas elevation in Deborah number and buoyancy ratio is found to suppress skin friction. The simulations are relevant to hydromagnetic nano-materials processing operations for coatings deployed in multi-functional tribological systems and surface protection.

Studying the Oscillating Flow around Unconfined Obstacle of Elliptical Cross-Section

The present paper focuses on the effect of geometric shape of a cylindrical body submerged in an oscillating flow by means of numerical investigations. The cylindrical body has an elliptic cross-section with a variation of its elliptic ratio (ratio between major and minor axes of the elliptic section). The flow direction is oriented along the major axis. Three regimes from (Tatstuno and Bearman) maps are studied namely, a symmetric regime A and two other asymmetric regimes D and F. The flow field structures, the Morison coefficients of longitudinal forces and the root mean square (r.m.s.) of transverse forces are computed with respect to the elliptic ratio variation. For the case of cylinders with slightly elliptic cross-section, vortices and pressure fields are very similar to those of a circular cylinder. For the case of regime A, the vortex shedding is always symmetric despite the unbreakable variation of the elliptic ratio. On the other hand, the reduction of the elliptic ratio weakens the asymmetry of the flow for regimes D and F. Moreover, the flow in each regime becomes completely symmetric at a given value of the elliptic ratio. In fact, the predicted longitudinal component of the force acting on the cylinder decreases with the reduction of this ratio. This results in the same manner on the behavior of Morison coefficients. With regard to the symmetric regime A, the transverse force does not manifest itself for all considered ratios. On the other hand, the transverse force in the case of asymmetric regimes decreases rapidly with increasing the ellipticity of the cylinder. The present study showed us that the inertia coefficient is sensitive to the vortex path; however, the drag coefficient is independent of the vortex path. Both coefficients depend simultaneously on Reynolds number and the geometric shape of the body.

Computational analysis of Darcy-Forchheimer relation, reduced gravity, and external applied magnetic field influence on radiative fluid flow and heat transfer past a sphere: Finite difference method

The study of radiation, Darcy-Forchheimer relation, and reduced gravity, effects on magnetohydrodynamic flow across a solid sphere immersed in porous material, is the focus of the current work. Coupled and nonlinear partial differential governing equations, are established to model the studied configuration. By using appropriate scaling variables, the resultant set of governing equations is converted to its dimensionless form. Based on these established equations, a numerical algorithm is written based on the finite element approach to solve the considered problem. A verification of the validity of the proposed model is done by comparing with already published results. Furthermore, to check the precision of solutions, a grid independence test has been accomplished. The unknown variables, such as fluid velocity and temperature, and their gradients are evaluated. This investigation's main objective is to demonstrate how the Darcy-Forchheimer law and reduced gravity due to density difference affect the natural convective heat transfer across a solid sphere immersed in a porous medium. Results show that the flow intensity decreases with the magnetic field parameter, local inertial coefficient, Prandtl number, and porosity parameter and becomes more important by increasing the reduced gravity and radiation parameters. In addition, the temperature increases with the inertial coefficient, porosity parameter, Prandtl number, radiation parameter, and magnetic field parameter and get declined with the reduced gravity parameter.

Numerical study on wind profiles change trend of upright reticulation barriers under different configuration models

To explore how to lay the same specifications to maximize the protection benefits of mechanical sand barriers is an essential issue in the actual production process. We used the Reynolds-Averaged Navier-Stokes (RANS) method and the shear stress transport (SST) K-ε turbulence model to study the windbreak efficiency of sand barriers with different structures. Among them, the structure of the sand barriers includes rhombus 60° (cTnI = 60°, R60°), rhombus 90° (cTnI = 90°, R90°), rhombus 120° (cTnI = 120°, R120°) and parallel straight line (belt). The sand barrier was set to a porous jump model, where the surface permeability a was 2.6 × 108, and the inertial resistance coefficient c2 was 9,400. The wind velocity field results showed that the sand barrier’s blocking effect on wind velocity decreases with the increase in height. The leading edge of the 120° obstacle has the strongest weakening effect on the inlet wind speed. The minimum wind speed (0.97 m/s to 1.41 m/s) occurs near the sand barrier, and the vortex appears on both sides of the node, and the wind speed increases. The order of the blocking effect of different angles on airflow is as follows: 120° > 90°> brand >60°. Under R120° conditions, the wind speed is reduced by more than 60% at 0.05 m and 0.1 m height behind the barrier compared to the initial wind speed. This will be conducive to the design and control engineering planning of the laying angle of the gauze sand barrier in the main wind direction.

Optimal frequency control for wind power-integrated power system based on parameter identification

Frequency control based on wind power is required by the grid code for maintaining system inertia level as well as frequency stability. However, synchronous generator (SG)-emulated frequency control of wind power will result in a nadir and second dip of frequency trajectory after a disturbance, which may threaten system safety. Optimizing the frequency trajectory of system to improve the nadir and avoid second dip usually relies on grid-wide information. But the information is hardly perfectly acquired in advance for real power system since it may change anytime. To address these problems, an optimal frequency control method for wind power-integrated power system based on parameter identification is proposed. Frequency characteristics of wind power-integrated are firstly analyzed based on the common frequency theory. Then the control framework of proposed method to eliminate the nadir and second dip of frequency trajectory is introduced. To realize this framework, system equivalent parameters like inertia and damp coefficient are identified by the extended Kalman smoother algorithm after each disturbance. These parameters are furtherly utilized to shape the transfer function of wind power-integrated power system as a first-order system. Finally, the implementation steps of proposed method are presented. The effectiveness of proposed method is verified by case studies.

Experimental study of surface roughness effects on hydrodynamic characteristics of a submerged floating tunnel

Marine biofouling is a major concern in the operational performance of submerged floating tunnels (SFTs). The objective of this research is to investigate the effects of marine fouling (represented by surface roughness) on the hydrodynamic behavior of SFTs, including the hydrodynamic forces on the SFT subject to current-only, wave-only, and combined current-wave flow conditions. The effects of increased surface roughness induced by marine fouling on the dynamic response of an SFT are characterized by hydrodynamic force coefficients, including drag and inertia coefficients. At the Water Lab of Delft University of Technology (TU Delft), experiments have been performed in a wave-current flume to compare the SFTs’ behaviors as affected by different roughness characteristics. In addition, a parametric cross-section for an SFT is presented, and the hydrodynamic performance associated with surface roughness effects on the parametric shape and circular SFT cross-section shape are compared. The results show that the parametric shape can effectively reduce the drag coefficient (Cd) under current-only conditions and lower the inertia coefficient (Cm) when waves are present. As roughness height and coverage ratio increase, Cd generally increases while Cm decreases. However, small differences in Cd and Cm can be observed with regard to roughness parameters for wave-only conditions. The Morison coefficients adapted for a marine-fouled SFT measured in the experiments are compared to predictions from engineering standards and are recommended for engineering practice.

Experimental Investigation of Fluid Flow through Zinc Open-Cell Foams Produced by the Excess Salt Replication Process and Suitable as a Catalyst in Wastewater Treatment

The “excess salt replication process” is a new simple method of fabrication of open-cell metal foam based on the commonly known salt replication method. Porous materials with porosity between 46% and 66% result when the employed alloy is 25% antimonial lead alloy and when it is 58% to 65% zamak 5. These foams are proposed as structured catalysts instead of packed beds in the treatment of wastewater. The local regimes influencing macroscopic air flow behaviour through these foams are delimited and boundaries are analysed in terms of sample length. Most of the experimental tests in this work exhibited a general trend of air flow in ESR foams dominated by the “strong inertia regime”. It was established that the law governing the unidirectional air flow through these foams was the full cubic law. The permeability and inertia coefficient of five samples with a cell diameter between 2.5 and 4.5 mm were calculated, and an empirical correlation was fitted. The irregular cuboid shape of salt grains used in the ESR foam was the origin of the special cell form of ESR foams leading to an anisotropic ordered porous media. This can explain the macroscopic turbulence of air flow because there were many dead zones present in the corner of each cubic cell, thus causing kinetic energy loss starting at earlier regimes.

Nanoindentation test of a DLC coated high-speed steel substrate using a two-dimensional axisymmetric finite element method

Diamond-Like Carbon is a thin coating that has high hardness, chemical inertia and low coefficient of friction characteristics that can improve the performance of cutting tools and mechanical components. To identify the characteristics of this film it is important to carry out mechanical tests, such as nanoindentation, which can provide important information in understanding and improving coating techniques and, when combined with the finite element method, leads to more detailed results of material behavior during testing. Considering this, the present work aimed to study and apply a nanoindentation test simulation of a Diamond-Like Carbon coated high-speed steel specimen. The results of the indenter penetration versus load were compared with experimental data seeking correlation of the model. A great proximity was observed between the experimental results and the results obtained in the simulation. When comparing the final indentation force, a proximity of 93.9 % and 95.5 % was found for the model with only one indentation and with partial indentations, respectively, thus validating the created model. The impact of modifying the indenter tip radius for the partial indentation method was also evaluated. The tip radius variation did not have a significant impact on the results of final indentation force and material hardness. The material hardness was also obtained in the simulation, which was equal to the experimental: 9.25 GPa.

Irreversibility analysis of radiative flow of Prandtl nanofluid over a stretched surface in Darcy-Forchheimer medium with activation energy and chemical reaction

This communication elaborates the irreversibility analysis of the flow of Prandtl nanofluid along with thermal radiation past a permeable stretched surface embedded in a Darcy-Forchheimer medium. The activation and chemical impressions along with effects of thermophoretic and Brownian motion are as well examined. The flow symmetry of the problem is modeled mathematically and leading equations are rehabilitated into nonlinear ordinary differential equations (ODEs) through the assistance of suitable similarity variables. The Keller-box technique in MATLAB is employed to draw the impacts of the contributing elements on the velocity field, temperature distribution, and concentration. The impact of the Prandtl fluid parameter has mounting performance for the velocity whereas conflicting behavior is examined in the temperature profile. The achieved numerical results are matched correspondingly with the present symmetrical solutions in restrictive cases and fantastic agreement is scrutinized. In addition, the entropy generation uplifts for the growing values of the Prandtl fluid parameter, thermal radiation, and Brinkman number and decreases for growing numbers of the inertia coefficient parameter. It is also discovered that the coefficient of friction decreases for all parameters involved in the momentum equation. Features of nanofluids can be found in a variety of real-world fields, including microfluidics, industry, transportation, the military, and medicine.

Prediction of wave force on netting under strong nonlinear wave action

Under the strong nonlinear wave environment, accurate simulation of wave force for aquaculture netting is an effective guarantee for cage design and safety. In this paper, the horizontal wave forces of a nylon square-mesh netting panel were obtained through a series of strong nonlinear regular wave tests, and their nonlinearity was analyzed by amplitude spectrum. Moreover, the Morison equation based on fifth-order Stokes wave theory was used to reasonably predict the wave force on the netting. The results showed that both wave and wave force have strong nonlinearity, especially the latter. The frequency domain characteristics of the test wave and wave force are similar, while the higher frequency components of the test force are more apparent. The predicted wave forces are in good agreement with the test values in time and frequency domain, and zero or higher frequency components of predicted force are more prominent with the increase of wave steepness. When the range of the Keulegan-Carpenter number is 35-120, the average drag and inertia coefficient of the predicted force are 2.4 and 2.1, respectively. The results can provide a more accurate assessment of the nonlinear wave force on aquaculture facilities.

Postflight Recovery of the Rotational Motion of a Small Space Vehicle from Solar Sensor Information

The use of the developed technology for solving inverse problems of parametric identification of the rotational motion of a spacecraft (SC) based on the accumulated sample of measurements of various compositions is expanded. On the example of processing telemetry data (measuring the direction vector to the Sun) of the BugSat-1 small spacecraft (SSC), the possibility of determining not only the characteristics of rotational motion but also its inertia coefficient is demonstrated. The rotational motion is determined based on the data obtained for five time intervals from January to May 2022, during which BugSat-1 made an uncontrolled movement around the direction vector toward the Sun. This type of motion does not allow applying traditional approaches to determine the dynamics of its rotation. In the process of data processing, a simplified model of the rotation of a SSC is used. At the same time, the initial conditions of rotational motion are estimated—the angular velocity vector and orientation angles, which made it possible to draw a conclusion about the precessional motion of a SSC. Using the analytical model of a regular precession, it is possible to estimate the inertia coefficient of a SSC. The results of flight information processing are presented and the errors of the obtained results are estimated.

A new method to estimate the resistance coefficients of net panels modeled as porous media

Modeling net panels as thin porous media is an effective approach to carry out computational fluid dynamics (CFD) simulations of fishing nets and aquaculture cages. Existing methods to estimate the resistance coefficients for these porous media are based on simplified analytical models that relate these coefficients to the drag and lift coefficients of the panel. We propose a new method that uses a CFD model of the flow through a layer of porous media to estimate the resistance coefficients from regression analysis with experimental data. To increase the computational performance, the CFD model response is pre-calculated and interpolated in the regression analysis. The proposed method is applied to different net panels compared with existing methods. Results show that it provides better results than previous methods. Estimating both the inertial and the viscous resistance coefficients always provides better results than estimating just the inertial coefficients and it does not complicate the regression analysis with the proposed method. The method is easy to implement, fast and it could be used to estimate the resistance coefficients of materials other than net panels, since it does not make any assumption about the geometric characteristics of the actual material.

HYDRO-GAS-DYNAMIC MODEL OF MOTION OF GAS-SATURATED LIQUID IN A CENTRIFUGAL POROUS PUMP


 
 
 An approach has been developed to the formation of a theoretical model of the movement of a gas- saturated liquid in the flow path of a porous centrifugal pump, as an assembly of the system for feeding the reaction mass of liquid-propellant rocket engines. The developed approach is based on a physical model of the turbulent motion of a gas-liquid mixture, within which conservation equations are used. Two models are proposed that describe the movement of a gas-liquid mixture in the flow path of a centrifugal porous pump in a two-phase one- dimensional formulation and a quasi-homogeneous one, complementing each other. A porous impeller of a closed- type centrifugal pump of constant width is considered. The energy losses of the gas-liquid mixture flow at the inlet to the pump impeller, as well as the losses of disk friction associated with rotation in a fixed housing, are not taken into account. The parameters of the viscous and inertial hydraulic resistance coefficients of the porous body are used. In particular, the influence of the static pressure gradient in a gas-saturated liquid and the friction force on the accumulation of gas at the inlet to the impeller and the stability of the liquid supply by the pumping unit is noted. The use of the developed approach makes it possible, by calculation methods, to evaluate the values of parameters characterizing the movement of gas-liquid media in centrifugal porous pumps of the designed systems for feeding propellant components to liquid-propellant rocket engines, to reduce the amount of experimental testing of new and modernized propulsion systems for space stages and launch vehicles.
 
 

Nonlinear analysis of Darcy-Forchheimer flow in EMHD ternary hybrid nanofluid (Cu-CNT-Ti/water) with radiation effect

This article aims to explore the influence of non-linear Darcy-Forchheimer on the EMHD (Electromagnetohydrodynamic) flow of a couple stress water-based nanofluid, hybrid nanofluid, and ternary hybrid nanofluid with thermal radiation on a stretching sheet. The significant improvement in thermal efficiency and the energy exchange rate used in fuel dynamics and vehicle cooling has led to an increasing understanding of hybrid nanofluids. However, the concept of a water-based nanofluid containing three distinct solid nanoparticles (referred to as a ternary hybrid nanofluid) is nevertheless remarkable. The ternary hybrid nanoparticles copper (Cu), carbon nanotubes (CNT), and titanium (Ti) are suspended in the base fluid water (H2O). Established mathematical equations are nonlinear, which are resolved for velocity, the temperature in addition to the skin friction coefficient, and the rate of heat transfer by using bvp4c with MATLAB solver. The connotations of innumerable control parameters are exposed through graphical picturization and discussed in detail. The results were compared with specific references, and a righteous compromise was found. Increasing inertia coefficient values causes a decrease in velocity, but temperature causes a contradictory behavior in ternary hybrid nanofluids. The temperature profile is raised for the higher values of the Eckert number in the case ofn=0.5 and n=1.5. The ternary hybrid nanofluid has more influence than the nanofluid and hybrid nanofluid in the temperature profile.

The relationship between exchange rate volatility and inflation in Turkey

Purpose- Many studies pointing out that the exchange rate depreciations underlies of the inflation problem, which is still keep up to-date, provides empirical evidences about the existence of a direct relationship between the exchange rate and domestic prices. In addition to this phenomenon called exchange rate pass-through, we also think that exchange rate volatility can also have an impact on domestic prices. The aim of this study is to investigate the relationship between inflation and exchange rate volatility, which is characterized by the increase in risks and the creation of an environment of uncertainty in Turkish economy. Methodology- In our study, we run an augmented philips curve equation to estimate the effect of exchange rate volatility and other variables on inflation. We measure exchange rate volatility as the standard deviation and GARCH (1,1), which are frequently used in the literature. In addition, we use the time-varying parameter approach to estimate the direction in which the effect of exchange rate volatility on inflation changes over time. Findings- According to the findings, the parameters in the philips curve equation are statistically significant and reasonable in line with the economic theory. The coefficient of inflation inertia is estimated to be 0.33. This indicates that approximately one-third of a 1% increase in inflation comes from past inflation. The ERPT is calculated as 18% for the short term and 27% for the long term. The fact that the exchange rate volatility parameters are statistically significant confirms our hypothesis. Accordingly, an increase of 1 conditional standard deviation in exchange rate volatility leads to an increase in domestic prices by 0.71. We also provide evidences that the impact of both exchange rate and exchange rate volatility on inflation increases over time. Conclusion- The results show that, in addition to the exchange rate, exchange rate volatility also has a significant effect on inflation. This provides credible evidences that exchange rate uncertainty should be an additional indicator, such as the exchange rate, to achieve price stability and monetary policy goals. Keywords: Exchange rate volatility, exchange rate pass-through, inflation, time-series models, monetary policy JEL Codes: E31, C32, E52

Prediction and Validation of Flow Properties in Porous Lattice Structures

Abstract High-porosity metal foams have been extensively studied as an attractive candidate for efficient and compact heat exchanger design. With the advancements in additive manufacturing, such foams can be manufactured with controlled topology to yield highly tailorable mechanical and transport properties. In this study, a lattice Boltzmann method (LBM)-based pore-scale model is implemented to simulate the fluid flow in additively manufactured (AM) metal foams with unit cell topologies of Cube, Face Diagonal (FD)-Cube, Tetrakaidecahedron (TKD), and Octet lattices. The pressure gradient versus average velocity profiles predicted by the LBM model were validated against in-house measurements on the AM lattice samples with the same unit cell topologies. Based on the simulation results, a novel hybrid model is proposed to accurately predict the volume averaged flow properties (permeability and inertial coefficients) of the four structures. Specifically, the linear LBM (neglecting inertial forces) is first implemented to obtain the intrinsic permeability, and then the standard LBM is applied to obtain the inertial coefficient. Convenient correlations for those flow properties as a function of porosity and fiber diameter are constructed. The effects of the AM print qualities on the flow properties are also discussed. The advantages of the hybrid model compared to the polynomial fitting approach for determining flow properties are discussed and compared quantitatively. The hybrid model and presented results are valuable for flow and thermal transport evaluation when designing new metal foams for specific applications and with different materials and topologies. The presented correlations based on pore-scale simulations can also be conveniently used in volume-averaged models to predict the macroscale flow behavior in such complex structures.

Analysis of thermally radiative magnetized viscoelastic (second-grade) fluid by impermeable vertical cylinder

We made an attempt to disclose the phenomenon of dual stratification in magnetized viscoelastic second-grade fluid model generated by the movement of vertical cylinder. Mass and heat transportation is accounted under the aspects of Joule and Ohmic dissipations. The flow is coupled due to the consideration of nonlinear convected terms. Boundary-layer concept is implemented for the simplification of mathematical system. This system is made into the non-dimensional forms by reporting the similarity variables. The system of non-dimensional equations is executed with the use of homotopic criteria. The convergent region of solutions is reported and discussed. The convergent results are shown by graphical illustrations by considering distinct emerging constraint values. An increment in Darcy and inertia coefficient parameters corresponds to a decay in the flow. Temperature distribution is an increasing function of thermal Biot number and radiation parameter while it diminishes when thermal stratification parameter increases. Concentration is reduced for larger Schmidt number along with solutal stratification parameter. Besides the heat–mass transportation rates are increasing functions of thermo-solutal Biot numbers. The considered problem finds relevance in functional smart electro conductive enrobing coating processes in manufacturing. This is a principal application of the model studied where external axisymmetric boundary layers occur with combined magnetic, thermal and rheological effects.

Hydrodynamic loads of the bridge decks in wave-current combined flows

This work uses a Large Eddy Simulation (LES) model and the Volume of Fluid (VOF) scheme to investigate the hydrodynamic loads on submerged rectangular decks in wave-current combined flows. The influences of current velocity, wave height, deck length, and blockage ratio on the wave loads are examined, and a modified Morison equation is used to predict the hydrodynamic forces on the deck. The simulation results demonstrate that the wave loads are linearly proportional to wave height H when H ≤ 0.4h, h is the water depth. By setting the reference velocity as Ur = (gH)1/2 for wave-induced flow, the hydrodynamic loads can be separated into a steady term (current-induced load) and an acceleration term (wave-induced load). The crucial hydrodynamic load comes from the surface pressures on the upper side of the decks, owing to the deck length being much larger than the deck thickness. In addition, the drag coefficient is independent of the wave height H, aspect ratio L/D, and the Keulegan-Carpenter number KC; while the lift coefficient depends on the submergence ratio S/D. Bridge engineers could easily use the modified Morison equation and the maximum drag coefficient CD = 2.73, lift coefficient CL = −2.05, the inertia coefficients CMx = 0.95 and CMz = 2.53 to compute the maximum loads against wave-current combined flows.