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Hurricane‐induced compound flooding is a combined result of multiple processes, including overland runoff, precipitation, and storm surge. This study presents a dynamical coupling method applied at the boundary of a processes‐based hydrological model (the hydrological modeling extension package of the Weather Research and Forecasting model) and the two‐dimensional Regional Ocean Modeling System on the platform of the Coupled‐Ocean‐Atmosphere‐Wave‐Sediment Transport Modeling System. The coupled model was adapted to the Cape Fear River Basin and adjacent coastal ocean in North Carolina, United States, which suffered severe losses due to the compound flood induced by Hurricane Florence in 2018. The model's robustness was evaluated via comparison against observed water levels in the watershed, estuary, and along the coast. With a series of sensitivity experiments, the contributions from different processes to the water level variations in the estuary were untangled and quantified. Based on the temporal evolution of wind, water flux, water level, and water‐level gradient, compound flooding in the estuary was categorized into four stages: (I) swelling, (II) local‐wind‐dominated, (III) transition, and (IV) overland‐runoff‐dominated. A nonlinear effect was identified between overland runoff and water level in the estuary, which indicated the estuary could serve as a buffer for surges from the ocean side by reducing the maximum surge height. Water budget analysis indicated that water in the estuary was flushed 10 times by overland runoff within 23 days after Florence's landfall. Plain Language Summary Compound flooding refers to a phenomenon in which two or more flooding sources occur simultaneously or subsequently within a short period of time. In this study, we present a new numerical model that combines hydrological and ocean models to represent the exchange of water levels at the land‐ocean interaction zone. To test the model's robustness, we use this model to simulate the water level changes in Cape Fear River Basin and adjacent coastal ocean in North Carolina, United States, for Hurricane Florence in 2018. The comparison between observed and simulated water level prove that the new model can better resolve the changes in water elevation during a hurricane event than the traditional method where the ocean model utilized the river model's outputs as its boundary condition. We further quantify the contributions from different processes to the water level variations in the estuary. The compound flooding in the estuary was categorized into four stages: (I) swelling, (II) local‐wind‐dominated, (III) transition and (IV) overland‐runoff‐dominated. The estuary could serve as a buffer for surges from the ocean side by reducing the maximum surge height. The water in the estuary was flushed 10 times by overland runoff within 23 days after Florence's landfall. Key Points A coupled hydrological‐ocean model was developed using hydrological modeling extension package of the Weather Research and Forecasting model (WRF‐Hydro) and two‐dimensional Regional Ocean Modeling System (ROMS 2D) through the Coupled‐Ocean‐Atmosphere‐Wave‐Sediment Transport modeling system The dynamical coupling method was applied to the interface boundary of WRF‐Hydro and ROMS 2D to realize a seamless model coupling Hurricane Florence‐induced compound flooding event was investigated by analyzing the modeled water level evolution, water budget, and nonlinear effects in the Cape Fear Estuary

It is known that representing wetland dynamics in land surface modeling improves models ‘capacity to reproduce fluxes and land surface boundary conditions for atmospheric modeling in general circulation models. This study presents the development of the full coupling between the Noah-MP land surface model (LSM) and the HyMAP flood model in the NASA Land Information System and its application over the Inner Niger Delta (IND), a well-known hot-spot of strong land surface-atmosphere interactions in West Africa. Here, we define two experiments at 0.02o spatial resolution over 2002-2018 to quantify the impacts of the proposed developments on simulating IND dynamics. One represents the one-way approach for simulating land surface and flooding processes (1-WAY), i.e., Noah-MP neglects surface water availability, and the proposed two-way coupling (2-WAY), where Noah-MP takes surface water availability into account in the vertical water and energy balance. Results show that accounting for two-way interactions between Noah- MP and HyMAP over IND improves simulations of all selected hydrological variables. Compared to 1-WAY, evapotranspiration derived from 2-WAY over flooding zones doubles, increased by 0.8mm/day, resulting in an additional water loss rate of ~18,900km(exp 3)/year, ~40% drop of wetland extent during wet seasons and major improvement in simulated water level variability at multiple locations. Significant soil moisture increase and surface temperature drop were also observed. Wetland outflows decreased by 35%, resulting in a substantial a Nash-Sutcliffe coefficient improvement, from -0.73 to 0.79. It is anticipated that future developments in water monitoring and water-related disaster warning systems will considerably benefit from these findings.

With the development of urbanization and the application of renewable energy, wind turbine is becoming an important approach for wind energy reservation and utilization. This study provides a numerical investigation on understanding the surface pressure distribution, flow characteristics and dynamic responses of a parked straight‐bladed vertical axis wind turbine (VAWT), which is helpful for its design. Together with the two‐way coupling method between simulation platforms such as STAR‐CCM+ and ABAQUS, the SST k‐ω turbulence model is used to obtain the surface pressure and surrounding flow of the VAWT, and the finite element method is used to obtain the dynamic responses of its structural components. The results show that the contours of the pressure distribution on the windward surface of the VAWT are similar even under a few different conditions, and the deformation of the VAWT can lead to changes in surface pressure; the turbulent flow characteristics and the wake effect become more obvious as the wind velocity increases; the blades and support arms of the VAWT need to be reinforced during the design, and the effect of the parked condition on the dynamic responses of the VAWT can be neglected. The two‐way coupling method as well as the numerical simulation results is expected to provide references for the design of VAWTs subjected to coming wind action. This study provides a numerical investigation on understanding the surface pressure distribution, flow characteristics, and dynamic responses of a parked straight‐bladed vertical axis wind turbine with the two‐way coupling method between STAR‐CCM+ and ABAQUS. The research methods as well as the simulation results are expected to provide references for the design of vertical axis wind turbines subjected to coming wind action.

With the progress and development of science and technology, D fluid simulation technology is gradually moving towards a more systematic and comprehensive development. Of course, more and more people use the three D fluid simulation technology, which further promotes its development. In order to make the three fluid simulation technology more advanced and the whole society, it needs to be studied and improved [1].

Granular flows of 200 μm particles and the pile formation in a flat-bottomed hopper and bin in the presence of air and in a vacuum were predicted based on three-dimensional numerically empirical constitutive relations using Smoothed Particle Hydrodynamics and Computational Fluid Dynamics methods. The constitutive relations for the strain rate independent stress have been obtained as the functions of the Almansi strain including the large deformation by the same method as Yuu et al. [1]. The constitutive relations cover the elastic and the plastic regions including the flow state and represent the friction mechanism of granular material. We considered the effect of air on the granular flow and pile by the two-way coupling method. The granular flow patterns, the shapes of piles and the granular flow rates in the evolution are compared with experimental data measured under the same conditions. There was good agreement between these results, which suggests that the constitutive relations and the simulation method would be applicable for predicting granular flows and pile formation with complex geometry including free surface geometry. We describe the mechanisms by which the air decreases the granular flow rate and forms the convergence granular flow below the hopper outlet.

In this research, a two-way coupling of discrete phase model is developed in order to track the discrete nature of aluminum oxide particles in an obstructed duct with two side-by-side obstacles. Finite volume method and trajectory analysis are simultaneously utilized to solve the equations for liquid and solid phases, respectively. The interactions between two phases are fully taken into account in the simulation by considering the Brownian, drag, gravity, and thermophoresis forces. The effects of space ratios between two obstacles and particle diameters on different parameters containing concentration and deposition of particles and Nusselt number are studied for the constant values of Reynolds number (Re = 100) and volume fractions of nanoparticles (Φ = 0.01). The obtained results indicate that the particles with smaller diameter (dp = 30 nm) are not affected by the flow streamline and they diffuse through the streamlines. Moreover, the particle deposition enhances as the value of space ratio increases. A comparison between the experimental and numerical results is also provided with the existing literature as a limiting case of the reported problem and found in good agreement.

A numerical simulation of the particle-gas flow in a vertical turbulent pipe flow was conducted. The main objective of the present article is to investigate the effects of dispersed phase (particles) on continuous phase (gas). In so doing, two general forms of Eulerian-Lagrangian approaches namely, one-way (when the fluid flow is not affected by the presence of the particles) and two-way (when the particles exert a feedback force on the fluid) couplings were used to describe the equations of motion of the two-phase flow. Gas-phase velocities which are within the order of magnitude as that of particles, volume fraction, and particle Stokes number were calculated and the results were subsequently compared with the available experimental data. The simulated results show that when the particles are added, the fluid velocity is attenuated. With an increase in particle volume fraction, particle mass loading and Stokes number, velocity attenuation also increases. Moreover, the results indicate that an increase in particle Stokes number reduces the special limited particle volume fraction, according to which one-way coupling method yields plausible results. The results have also indicated that the significance of particle fluid interaction is not merely a function of volume fraction and particle Stokes number.

Clearance-fit (side-fit) spline joints are a key component in a permanent magnet synchronous motor (PMSM) in electric submersible pumping wells. The nonuniform spline clearance affects the output performance of a PMSM. A concept for energy conservation is optimized in this study to improve the modeling accuracy of electromagnetic torque. However, most existing computation models are one-way model with a magneto-mechanical simulation. In this study, a more accurate two-way coupling method is presented for simulating the electromagnetic and mechanical characteristics of PMSM. Additionally, importance should be attached to this two-way magneto-mechanical coupling methodology in an actual simulation. The coupled power, electrical and magnetic energy, and electromagnetic torque equations are solved iteratively until convergence for PMSMs with a segmented rotor and a non-segmented rotor. The optimal electromagnetic torque is obtained for different rotor configurations with the change of temperatures and rotational speeds. The results show that the output performance and electromagnetic torque of the PMSM are seriously affected by the effects of two-way magneto-mechanical coupling and nonuniform spline clearance. The proposed two-way coupling model gives more reasonable predictions than other one-way models do, because the power transfer between the electrical and magnetic energy can be modeled more accurately. The self-centralizing performance of clearance-fit splines and the sensitivity to the radial clearance magnitude lead to the reduction of the electromagnetic torque for the PMSM. Additionally, the electromagnetic torques decrease with the enhanced rotor temperatures and rotational speeds. The best rotor temperature and rotational speed are chosen through a comparison of the experimental results, and then the optimal electromagnetic torque is provided to ensure the output performance of the PMSM in electric submersible pumping wells.

DNS data of particle-laden jets are discussed both in the one- and two-way coupling regimes. Dynamics of inertial particles in turbulent jets is characterized by an anomalous transport that leads to the formation of particle concentration peaks along the jet axis. Larger is the particle inertia farther the peak location occurs. The controlling parameter is found to be the local large-scale Stokes number which decreases quadratically with the axial distance and is order one in coincidence of the peaks. The centerline mean particle velocity is characterized by two scaling laws. The former occurs upstream the location where the Stokes number is order one, and is linear in the axial distance with negative coefficient. The latter, occurring downstream where the local Stokes number is small, coincides with that of the centerline mean fluid velocity. This behavior affects the development of the particle-laden jet when the mass load of the particulate phase increases and two-way coupling effects become relevant. Two distinct behaviors for the jet development are found behind and beyond the location of unity local Stokes number leading to different scaling laws for the mean centerline fluid velocity.

The Yellow River Basin is a typical arid and semi-arid area, which is very sensitive to climate change. In recent years, it has become the area with the greatest shortage of water resources in China. In this study, a new two-way coupling model of land surface and hydrology has been explored to analyze the impacts of climate change and human activities on the runoff. It is of great theoretical and practical significance for making better management countermeasures and strategies to cope with climate change in the Yellow River Basin. The results showed that: (1) the annual average precipitation in the basin was 470.1 mm, which was higher in the lower reaches than in the middle and upper reaches. The annual average temperature is 5.8 °C. The entire basin showed a remarkable warming speed. The annual average pan evaporation is 1067.3 mm showing a downward trend throughout the basin; (2) from 1987 to 2009, the contribution rate of climate change to runoff change has not fluctuated by more than 5%. Since 2010, the precipitation caused by climate factors has increased runoff by 12~15%. The impact of land use change on runoff has been increasing annually. The influence of projects on runoff change was the leading factor of runoff reduction in the Yellow River Basin, with the contribution rate around 50%; and (3) for every 10% decrease in precipitation, the runoff decreases by 13~15.7%. When the temperature rises by 1.0 °C, the runoff decreases by 2.1~4.2%. The runoff in the upper reaches of the Yellow River was most sensitive to precipitation and temperature changes. This showed that the runoff in the plateau and mountainous areas were highly sensitive to climate change.