Waseda University · Engineering
Professor Takuya Terahara's research lab specializes in advanced computational mechanics, focusing on space–time isogeometric analysis (ST-IGA) and T-splines-based methods for solving complex fluid–structure interaction (FSI) problems. The lab develops high-fidelity numerical methods to address challenges in hemodynamics—particularly in heart valve and ventricle-aorta flow simulations—by enabling accurate boundary layer resolution and contact modeling without mesh protection gaps. The lab also extends these methods to aerospace applications, such as parachute deployment and re-entry vehicle aerodynamics, using complex-geometry T-spline mesh generation for high-accuracy simulations. Their work emphasizes robust, high-order discretization techniques that maintain smoothness and continuity across multi-dimensional structural interfaces.
Figures are computed from collected data and may differ slightly.
Abstract Heart valve fluid–structure interaction (FSI) analysis is one of the computationally challenging cases in cardiovascular fluid mechanics. The challenges include unsteady flow through a complex geometry, solid surfaces with large motion, and contact between the valve leaflets. We introduce here an isogeometric sequentially-coupled FSI (SCFSI) method that can address the challenges with an outcome of high-fidelity flow solutions. The SCFSI analysis enables dealing with the fluid and struc
Abstract We address the computational challenges of and presents results from ventricle-valve-aorta flow analysis. Including the left ventricle (LV) in the model makes the flow into the valve, and consequently the flow into the aorta, anatomically more realistic. The challenges include accurate representation of the boundary layers near moving solid surfaces even when the valve leaflets come into contact, computation with high geometric complexity, anatomically realistic representation of the LV
Abstract In this second part of a two-part article, we provide an overview of the heart valve flow analyses conducted with boundary layer and contact representation, made possible with the space–time (ST) computational methods described in the first part. With these ST methods, we are able to represent the boundary layers near moving solid surfaces, including the valve leaflet surfaces, with the accuracy one gets from moving-mesh methods and without the need for leaving a mesh protection gap bet
Abstract We present a T-splines computational method and its implementation where structures with different parametric dimensions are connected with continuity and smoothness. We derive the basis functions in the context of connecting structures with 2D and 1D parametric dimensions. Derivation of the basis functions with a desired smoothness involves proper selection of a scale factor for the knot vector of the 1D structure and results in new control-point locations. While the method description
Abstract In this second part of a two-part article, we present spacecraft parachute structural mechanics computations with the T-splines computational method introduced in the first part. The method and its implementation, which was also given in the first part, are for computations where structures with different parametric dimensions are connected with continuity and smoothness. The basis functions of the method were derived in the context of connecting structures with 2D and 1D parametric dim
Abstract We present, as a 3D application of recently introduced Complex-Geometry T-Splines Mesh Generation (CGTSMG) method, Space–Time Isogeometric Analysis (ST-IGA) of spacecraft parachute aerodynamics. The computation is for the final design of the Orion spacecraft landing parachute. The parachute canopy has hundreds of gaps and slits, which are modeled, and a wider gap and 16 “windows,” which are resolved. We first generate, manually next to the canopy surfaces and with the Complex-Geometry I
Fluid mechanics computation of a heart valve with an interface-tracking (moving-mesh) method was one of the classes of computations targeted in introducing the space-time (ST) interface tracking method with topology change (ST-TC). The method was introduced with finite element descritization. Now, we apply the method to isogeometric analysis (IGA) to calculate more accurate computation, and simplify the master-slave system in ST-TC method towards fluid-structure interaction (FSI) analysis.
In this paper, we present fluid mechanics computation of left ventricle, aorta and aortic valves. We use an interface-tracking method, which is based on the space–time slip-interface, topology change and isogeometric discretization methods. The method allows us to obtain the accurate flow solution also near the boundaries when the leaflets come into contact. In addition, the flow computation with the aorta and the left ventricle make the solution more realistic.
Abstract We present a T-splines mesh generation method for complex geometries, enabling good local mesh refinement in isogeometric analysis (IGA), with the continuity and smoothness desired. Good local mesh refinement enhances the IGA computational efficiency by having a higher density of control points only in places and directions where we need higher refinement. It also enhances computational robustness by evading high-aspect-ratio elements associated with directional refinement of structured
Heart valve flow analysis requires accurate representation of boundary layers near moving surfaces, even when the leaflets come into contact, and handling high geometric complexity. We address these challenges with a space-time (ST) method that integrates three ST methods in the framework of the ST-VMS method: the ST Slip Interface (ST-SI) and ST Topology Change (ST-TC) methods and ST Isogeometric Analysis (ST-IGA). The ST-VMS, as a moving-mesh method, maintains high-resolution boundary layer re
In this study, we present a novel method for modeling the canopy surface of an umbrella. Our approach involves representing the area between the ribs on the canopy as a trimmed bilinear patch. Furthermore, we conduct an in-depth exploration of various differential geometric properties of the umbrella surface. We introduce a method for unfolding the canopy surface onto a plane, which serves as a valuable technique for fabricating a cardboard template to accurately cut canopy fabrics. To validate
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