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Given the complexity of human left heart anatomy and valvular structures, the fluid–structure interaction (FSI) simulation of native and prosthetic valves poses a significant challenge for numerical methods. In this review, recent numerical advancements for both fluid and structural solvers for heart valves in patient-specific left hearts are systematically considered, emphasizing the numerical treatments of blood flow and valve surfaces, which are the most critical aspects for accurate simulations. Numerical methods for hemodynamics are considered under both the continuum and discrete (particle) approaches. The numerical treatments for the structural dynamics of aortic/mitral valves and FSI coupling methods between the solid Ωs and fluid domain Ωf are also reviewed. Future work toward more advanced patient-specific simulations is also discussed, including the fusion of high-fidelity simulation within vivo measurements and physics-based digital twining based on data analytics and machine learning techniques. 

In meandering rivers, interactions between flow, sediment transport, and bed topography affect diverse processes, including bedform development and channel migration. Predicting how these interactions affect the spatial patterns and magnitudes of bed deformation in meandering rivers is essential for various river engineering and geoscience problems. Computational fluid dynamics simulations can predict river morphodynamics at fine temporal and spatial scales but have traditionally been challenged by the large scale of natural rivers. We conducted coupled large‐eddy simulation and bed morphodynamics simulations to create a unique database of hydro‐morphodynamic data sets for 42 meandering rivers with a variety of planform shapes and large‐scale geometrical features that mimic natural meanders. For each simulated river, the database includes (a) bed morphology, (b) three‐dimensional mean velocity field, and (c) bed shear stress distribution under bankfull flow conditions. The calculated morphodynamics results at dynamic equilibrium revealed the formation of scour and deposition patterns near the outer and inner banks, respectively, while the location of point bars and scour regions around the apexes of the meander bends is found to vary as a function of the radius of curvature of the bends to the width ratio. A new mechanism is proposed that explains this seemingly paradoxical finding. The high‐fidelity simulation results generated in this work provide researchers and scientists with a rich numerical database for morphodynamics and bed shear stress distributions in large‐scale meandering rivers to enable systematic investigation of the underlying phenomena and support a range of river engineering applications.

 

Marine hydrokinetic (MHK) power generation systems enable harvesting energy from waterways without the need for water impoundment. A major research challenge for numerical simulations of field‐scale MHK farms stems from the large disparity in scales between the size of waterway and the energy harvesting device. We propose a large‐eddy simulation (LES) framework to perform high‐fidelity, multiresolution simulations of MHK arrays in a real‐life marine environment using a novel unstructured Cartesian flow solver coupled with a sharp‐interface immersed boundary method. The potential of the method as a powerful engineering design tool is demonstrated by applying it to simulate a 30 turbine MHK array under development in the East River in New York City. A virtual model of the MHK power plant is reconstructed from high‐resolution bathymetry measurements in the East River and the 30 turbines placed in 10 TriFrame arrangements as designed by Verdant Power. A locally refined, near the individual turbines, background unstructured Cartesian grid enables LES across a range of geometric scales of relevance spanning approximately 5 orders of magnitude. The simulated flow field is compared with a baseline LES of the flow in the East River without turbines. While velocity deficits and increased levels of turbulence kinetic energy are observed in the vicinity of the turbine wakes, away from the turbines as well as on the water surface only a small increase in mean momentum is found. Therefore, our results point to the conclusion that MHK energy harvesting from large rivers is possible without a significant disruption of the river flow.