Comparison of power losses in intra-atrial and extra-cardiac total cavo-pulmonary connections using computational fluid dynamic techniques

2021 ◽  
Author(s):  
Ravi S. Doddasomayajula
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Power Losses ◽  
Dynamic Techniques

On the influence of helix angle and face width on gear windage losses

2015 ◽  
Vol 230 (7-8) ◽  
pp. 1101-1112 ◽  
Author(s):  
Nicolas Voeltzel ◽  
Yann Marchesse ◽  
Christophe Changenet ◽  
Fabrice Ville ◽  
Philippe Velex
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Helix Angle ◽  
Spur Gears ◽  
Power Losses ◽  
Flow Rates ◽  
Helical Gears ◽  
Face Width ◽  
Loss Prediction ◽  
Simulated Flow

This paper investigates the windage power losses generated by helical gears rotating in pure air based on experimental results and a computational fluid dynamic code. It is found that the simulated flow patterns are totally different from those calculated for spur gears and that both tooth face width and helix angle are influential. The windage losses derived from Dawson’s and Townsend’s formulae are critically assessed using computational fluid dynamic results thus highlighting the limits of a unique formulation for accurate windage loss prediction. Finally, an analytical approach is suggested which gives good results providing that the flow rates at the boundaries of the inter-tooth domains can be estimated.

scholarly journals Turbulent and Transitional Modeling of Drag on Oceanographic Measurement Devices

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
J. P. Abraham ◽  
J. M. Gorman ◽  
F. Reseghetti ◽  
E. M. Sparrow ◽  
W. J. Minkowycz
Keyword(s):  
Global Warming ◽  
Drag Coefficient ◽  
Computational Fluid Dynamic ◽  
Rate Equation ◽  
Fluid Dynamic ◽  
Heat Content ◽  
Fall Rate ◽  
Dynamic Techniques ◽  
Measurement Devices

Computational fluid dynamic techniques have been applied to the determination of drag on oceanographic devices (expendable bathythermographs). Such devices, which are used to monitor changes in ocean heat content, provide information that is dependent on their drag coefficient. Inaccuracies in drag calculations can impact the estimation of ocean heating associated with global warming. Traditionally, ocean-heating information was based on experimental correlations which related the depth of the device to the fall time. The relation of time-depth is provided by a fall-rate equation (FRE). It is known that FRE depths are reasonably accurate for ocean environments that match the experiments from which the correlations were developed. For other situations, use of the FRE may lead to depth errors that preclude XBTs as accurate oceanographic devices. Here, a CFD approach has been taken which provides drag coefficients that are used to predict depths independent of an FRE.

An Assessment of Computational Fluid Dynamic Techniques in the Analysis and Design of Turbomachinery—The 1990 Freeman Scholar Lecture

1991 ◽  
Vol 113 (3) ◽  
pp. 315-352 ◽  
Author(s):  
B. Lakshminarayana
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
Grid Generation ◽  
Physical Models ◽  
Navier Stokes ◽  
Implicit Time ◽  
Computational Techniques ◽  
Validation Data ◽  
Analysis And Design ◽  
Dynamic Techniques

The objective of this paper is to review and assess various computational fluid dynamic techniques used for the analysis and design of turbomachinery. Assessments of accuracy, efficiency, range of applicability, effect of physical approximations, and turbulence models are carried out. Suggestions are made as to the most appropriate technique to be used in a given situation. The emphasis of the paper is on the Euler and Navier-Stokes solvers with a brief assessment of boundary layer solutions, quasi three-dimensional and quasi-viscous techniques. A brief review of the techniques and assessment of the following methods are carried out: pressure-based method, explicit and implicit time marching techniques, pseudo-compressibility technique for incompressible flow, and zonal techniques. Recommendations are made with regard to the most appropriate technique for various flow regimes and types of turbomachinery, incompressible and compressible flows, cascades, rotors, stators, liquid-handling and gas-handling turbomachinery. Computational fluid dynamics has reached a high level of maturity; Euler codes are routinely used in design and analysis, and the Navier-Stokes codes will also be commonplace before the end of this decade. But to capture the realism in turbomachinery rotors and multi-stage turbomachinery, it is necessary to integrate the physical models along with the computational techniques. Turbulence and transition modeling, grid generation, and numerical techniques play a key role. Finally, recommendations are made for future research, including the need for validation data, improved acceleration schemes, techniques for two-phase flow, improved turbulence and transition models, development of zonal techniques, and grid generation techniques to handle complex geometries.

Evaluation of side spillage for a hypersonic air intake using computational fluid dynamic techniques

2016 ◽  
Vol 231 (11) ◽  
pp. 2111-2119 ◽  
Author(s):  
Afroz Javed ◽  
Debasis Chakraborty
Keyword(s):  
Computational Fluid Dynamic ◽  
Fluid Dynamic ◽  
A Priori ◽  
Side Wall ◽  
A Priori Estimate ◽  
Capture Ratio ◽  
Initial Design ◽  
Mass Capture ◽  
Air Intake ◽  
Dynamic Techniques

Mass capture ratio of a hypersonic air intake is one of the most important performance parameters. However, no a priori estimate of its value exists for use in initial design exercise of a hypersonic vehicle. In the present work, an air intake of a non-axisymmetric scramjet engine, designed using stream thrust methodology, is studied using computational fluid dynamic techniques. A large amount of air mass flow rate is observed to spill from the sides, which is not accounted for in the initial design phase. In absence of even an approximate estimate of this spillage, computational fluid dynamic studies become the only available tool to evaluate the mass capture ratio. Simulations are also carried out with a side wall at the intake to stop spillage. Although mass capture ratio and static pressure at combustor entry improve, deterioration in other flow parameters such as static temperature, Mach number and total pressure is observed.

Sign in / Sign up

Export Citation Format

Share Document