Non-Boundary Conforming Methods for Large-Eddy Simulations of Biological Flows

2004 ◽  
Author(s):  
Elias Balaras ◽  
Jianming Yang
Keyword(s):  
Body Surface ◽  
Computational Algorithm ◽  
The Body ◽  
Large Eddy Simulations ◽  
Moving Boundaries ◽  
Lagrangian Formulation ◽  
Governing Equations ◽  
Large Eddy ◽  
Biological Flows ◽  
Boundary Conforming

In the present paper a computational algorithm suitable for large-eddy simulations of fluid/structure problems that are commonly encountered in biological flows is presented. It is based on a mixed Eurelian-Lagrangian formulation, where the governing equations are solved on a fixed grid, which is not aligned with the body surface, and the non-slip conditions are enforced via local reconstructions of the solution near the solid interface. With this strategy we can compute the flow around complex stationary/moving boundaries and at the same time maintain the efficiency and optimal conservation properties of the underlying Cartesian solver. A variety of examples, that establish the accuracy and range of applicability of the method are included.

Nonboundary Conforming Methods for Large-Eddy Simulations of Biological Flows

2005 ◽  
Vol 127 (5) ◽  
pp. 851-857 ◽  
Author(s):  
Elias Balaras ◽  
Jianming Yang
Keyword(s):  
Body Surface ◽  
Computational Algorithm ◽  
The Body ◽  
Large Eddy Simulations ◽  
Moving Boundaries ◽  
Lagrangian Formulation ◽  
Governing Equations ◽  
Solid Interface ◽  
Large Eddy ◽  
Biological Flows

In the present paper a computational algorithm suitable for large-eddy simulations of fluid/structure problems that are commonly encountered in biological flows is presented. It is based on a mixed Eurelian-Lagrangian formulation, where the governing equations are solved on a fixed grid, which is not aligned with the body surface, and the nonslip conditions are enforced via local reconstructions of the solution near the solid interface. With this strategy we can compute the flow around complex stationary/moving boundaries and at the same time maintain the efficiency and optimal conservation properties of the underlying Cartesian solver. A variety of examples, that establish the accuracy and range of applicability of the method are included.

Large-Eddy Simulations of Submarine Propellers

2015 ◽  
Vol 59 (04) ◽  
pp. 227-237
Author(s):  
Elias Balaras ◽  
Seth Schroeder ◽  
Antonio Posa
Keyword(s):  
Computational Cost ◽  
Open Water ◽  
The Body ◽  
Large Eddy Simulations ◽  
Immersed Boundary ◽  
Tip Vortices ◽  
Marine Propellers ◽  
Acoustic Signature ◽  
Large Eddy ◽  
Water Conditions

High-fidelity, eddy-resolving, simulations of marine propellers are challenging due to the coexistence of moving and stationary elements within the computational box, as well as the need to accurately resolve the dynamics of wake structures such as the tip and hub vortices, which have an effect on the acoustic signature of underwater vehicles. Although an isolated propeller in open-water conditions can be simulated in a rotating reference frame, in a computation involving the body of an appended submarine, e.g., the relative motion needs to be properly treated. This increases the computational cost and reduces the accuracy/robustness of typical body-fitted approaches. In this work, an immersed boundary formulation is utilized to perform large-eddy simulations of a propeller in open-water conditions and in the presence of an upstream appendage at zero incidence. In such case, the requirement for the grid to conform to the moving body is relaxed—solution is locally reconstructed to satisfy boundary conditions—and efficient, conservative structured solvers can be used. This enables us to capture the detailed dynamics of the tip vortices and their footprint on the statistics of the wake. The influence of the upstream appendage is also assessed.

scholarly journals An Effective Three-Dimensional Layout of Actuation Body Force for Separation Control

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Ittetsu Kaneda ◽  
Satoshi Sekimoto ◽  
Taku Nonomura ◽  
Kengo Asada ◽  
Akira Oyama ◽  
...  
Keyword(s):  
Body Force ◽  
Separation Bubble ◽  
Three Dimensional ◽  
Separated Flow ◽  
Flow Fields ◽  
The Body ◽  
Large Eddy Simulations ◽  
Separation Control ◽  
Large Eddy

We conducted large eddy simulations of the control of separated flow over an airfoil using body forces and discuss the role of a three-dimensional vortex structure in separation control. Two types of cases are examined: (1) the body force is distributed in a spanwise uniform layout and (2) the body force is distributed in a spanwise intermittent layout, with three-dimensional vortices being expected to be generated in the latter cases. The flow fields in the latter cases have a shorter separation bubble than those in the former cases although the total momentum of the body force in the latter cases is the same as or half of the former cases. In the flow fields of the latter type, the three-dimensional vortices, which are not observed in the former cases, are generated by the body force downstream of the body force distributed. Thus, three-dimensional vortices are considered to be effective in controlling the separated flow.

scholarly journals High-order LES of the flow over a simplified car model

2009 ◽  
pp. 627-646
Author(s):  
Matthieu Minguez ◽  
Richard Pasquetti ◽  
Eric Serre
Keyword(s):  
Reynolds Number ◽  
Low Reynolds Number ◽  
Fourier Method ◽  
High Order ◽  
The Body ◽  
Large Eddy Simulations ◽  
Vanishing Viscosity ◽  
Chebyshev Collocation ◽  
Car Model ◽  
Large Eddy

We study the influence of the Reynolds number on the Ahmed body flow for the subcritical incidence . =25°. Large Eddy Simulations (LES) have been performed at low Reynolds number Re=8322, in agreement with the experiments of Spohn and Gillieron (2002), for the configuration used by Lienhart et al. (2002) at Re=768000. Our simulations, based on a spectral Chebyshev collocation-Galerkin Fourier method, have been carried out with a parallel multi-domain solver. The LES capability is implemented by a Spectral Vanishing Viscosity (SVV) technique. The results globally point out that the topology of the flow is essentially determined by the body geometry.

The Role of Computer Modeling in Electrocardiography

1990 ◽  
Vol 29 (04) ◽  
pp. 282-288 ◽  
Author(s):  
A. van Oosterom
Keyword(s):  
Electrical Activity ◽  
Computer Modeling ◽  
Body Surface ◽  
Electrical Current ◽  
The Body ◽  
Volume Conductor ◽  
Current Generator ◽  
Cardiac Electrical Activity ◽  
Source Models

AbstractThis paper introduces some levels at which the computer has been incorporated in the research into the basis of electrocardiography. The emphasis lies on the modeling of the heart as an electrical current generator and of the properties of the body as a volume conductor, both playing a major role in the shaping of the electrocardiographic waveforms recorded at the body surface. It is claimed that the Forward-Problem of electrocardiography is no longer a problem. Several source models of cardiac electrical activity are considered, one of which can be directly interpreted in terms of the underlying electrophysiology (the depolarization sequence of the ventricles). The importance of using tailored rather than textbook geometry in inverse procedures is stressed.

The use of Body Surface Index as a Better Clinical Health indicators Compare to Body Mass Index and Body Surface Area for Clinical Application

2018 ◽  
pp. 131-136
Author(s):  
Shirazu I. ◽  
Theophilus. A. Sackey ◽  
Elvis K. Tiburu ◽  
Mensah Y. B. ◽  
Forson A.
Keyword(s):  
Surface Area ◽  
Body Surface Area ◽  
Clinical Application ◽  
Body Surface ◽  
Body Height ◽  
Health Indicators ◽  
The Body ◽  
Body Parameters ◽  
The Relationship ◽  
Individual Body

The relationship between body height and body weight has been described by using various terms. Notable among them is the body mass index, body surface area, body shape index and body surface index. In clinical setting the first descriptive parameter is the BMI scale, which provides information about whether an individual body weight is proportionate to the body height. Since the development of BMI, two other body parameters have been developed in an attempt to determine the relationship between body height and weight. These are the body surface area (BSA) and body surface index (BSI). Generally, these body parameters are described as clinical health indicators that described how healthy an individual body response to the other internal organs. The aim of the study is to discuss the use of BSI as a better clinical health indicator for preclinical assessment of body-organ/tissue relationship. Hence organ health condition as against other body composition. In addition the study is `also to determine the best body parameter the best predict other parameters for clinical application. The model parameters are presented as; modeled height and weight; modelled BSI and BSA, BSI and BMI and modeled BSA and BMI. The models are presented as clinical application software for comfortable working process and designed as GUI and CAD for use in clinical application.

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