scholarly journals Three-dimensional numerical investigation of flow through screens as energy dissipators

2017 ◽  
Vol 44 (10) ◽  
pp. 850-859 ◽  
Author(s):  
Rasoul Daneshfaraz ◽  
Sina Sadeghfam ◽  
Ali Ghahramanzadeh
Keyword(s):  
Energy Dissipation ◽  
Three Dimensional ◽  
Hydraulic Structures ◽  
Proof Of Concept ◽  
Flow Equations ◽  
Local Complex ◽  
Energy Dissipators ◽  
Flow Through ◽  
Surface Profiles ◽  
Supercritical Flows

Screens, perforated units to dissipate energy in hydraulic structures, are investigated numerically in this study. These units are part of a physical setup exposed to supercritical flows, normally created by sluice gates. The interaction of perforated screens and supercritical flows results in local complex three-dimensional flows, which can be analyzed by the application of RANS-based flow equations. The most important controlling parameters include supercritical Froude number between 2 and 10 and screen porosity of 40% and 50%. Numerical water surface profiles and energy dissipation are validated by the author’s experimental data. This paper derives a set of equations in terms of depth ratio of the hydraulic jump through the perforated screens and assesses the effect of baffles on energy dissipation. This study seeks a proof-of-concept for the application of the RANS-based technique for further application of the result to real hydraulic structures in due course.

scholarly journals Flow Over Embankment Gabion Weirs in Free Flow Conditions

2021 ◽  
Author(s):  
Roya Biabani ◽  
Farzin Salmasi ◽  
Meysam Nouri ◽  
John Abraham
Keyword(s):  
Energy Dissipation ◽  
Three Dimensional ◽  
Relative Energy ◽  
Physical Models ◽  
Flow Conditions ◽  
Environmental Aspects ◽  
Discharge Coefficients ◽  
Filling Materials ◽  
Surface Profiles ◽  
Crest Length

Abstract Gabion weirs have been widely used in rivers restoration and diversion water projects because of their hydro-environmental aspects and eco-friendly features. In this study, a series of laboratory tests were performed to investigate the effects of side ramp slope, crest length, and porous media properties on the flow regimes, water-surface profiles, discharge coefficients, and energy dissipation in embankment gabion weirs with upstream and downstream slopes. 24 physical models of solid and gabion weirs with three different upstream/downstream slopes (90°, 45° and 26.5°) were created. For gabion weirs, three different filling materials were tested. To investigate the complexity of flow over the porous-fluid interface and through the porous material, three-dimensional (3D) numerical simulations were developed. The results show that decreasing upstream slopes, from 90º to 26.5º, leads to decreased discharge coefficients. However, in all cases, gabion weirs lead to greater discharge coefficients than those of similar solid weirs. For milder side slopes, discharge ratios passing through all faces of the gabion weirs decreased nonlinearly. Moreover, with increasing the inlet discharge, relative energy dissipation was reduced up to 45% in gabion weirs.

scholarly journals A 3D hydrodynamic flow-focusing device for cell sorting

2021 ◽  
Vol 25 (3) ◽  
Author(s):  
Xiaofei Yuan ◽  
Andrew Glidle ◽  
Hitoshi Furusho ◽  
Huabing Yin
Keyword(s):  
Cell Sorting ◽  
Control Strategies ◽  
Three Dimensional ◽  
Hydrodynamic Flow ◽  
Proof Of Concept ◽  
Flow Focusing ◽  
Hydrodynamic Focusing ◽  
Cell Handling ◽  
Fluid Flow Control ◽  
High Degree

AbstractOptical-based microfluidic cell sorting has become increasingly attractive for applications in life and environmental sciences due to its ability of sophisticated cell handling in flow. The majority of these microfluidic cell sorting devices employ two-dimensional fluid flow control strategies, which lack the ability to manipulate the position of cells arbitrarily for precise optical detection, therefore resulting in reduced sorting accuracy and purity. Although three-dimensional (3D) hydrodynamic devices have better flow-focusing characteristics, most lack the flexibility to arbitrarily position the sample flow in each direction. Thus, there have been very few studies using 3D hydrodynamic flow focusing for sorting. Herein, we designed a 3D hydrodynamic focusing sorting platform based on independent sheath flow-focusing and pressure-actuated switching. This design offers many advantages in terms of reliable acquisition of weak Raman signals due to the ability to precisely control the speed and position of samples in 3D. With a proof-of-concept demonstration, we show this 3D hydrodynamic focusing-based sorting device has the potential to reach a high degree of accuracy for Raman activated sorting.

scholarly journals A Proof-of-Concept Algorithm for the Retrieval of Total Column Amount of Trace Gases in a Multi-Dimensional Atmosphere

2021 ◽  
Vol 13 (2) ◽  
pp. 270
Author(s):  
Adrian Doicu ◽  
Dmitry S. Efremenko ◽  
Thomas Trautmann
Keyword(s):  
Trace Gases ◽  
Three Dimensional ◽  
Principal Component ◽  
Radiative Transfer Model ◽  
Computational Time ◽  
Transfer Model ◽  
Proof Of Concept ◽  
Discrete Ordinate ◽  
Distribution Method ◽  
Total Column

An algorithm for the retrieval of total column amount of trace gases in a multi-dimensional atmosphere is designed. The algorithm uses (i) certain differential radiance models with internal and external closures as inversion models, (ii) the iteratively regularized Gauss–Newton method as a regularization tool, and (iii) the spherical harmonics discrete ordinate method (SHDOM) as linearized radiative transfer model. For efficiency reasons, SHDOM is equipped with a spectral acceleration approach that combines the correlated k-distribution method with the principal component analysis. The algorithm is used to retrieve the total column amount of nitrogen for two- and three-dimensional cloudy scenes. Although for three-dimensional geometries, the computational time is high, the main concepts of the algorithm are correct and the retrieval results are accurate.

Poly-(lactic acid) and fibrin bioactive cellularized scaffold for use in bone regenerative medicine: Proof of concept

2021 ◽  
pp. 088391152199640
Author(s):  
Renata Aquino de Carvalho ◽  
Valmir Vieira Rocha Júnior ◽  
Antonio José Felix Carvalho ◽  
Heloisa Sobreiro Selistre de Araújo ◽  
Mônica Rosas Costa Iemma ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Regenerative Medicine ◽  
Platelet Rich Plasma ◽  
Three Dimensional ◽  
Culture Conditions ◽  
Infrapatellar Fat Pad ◽  
Dimensional Structure ◽  
Poly Lactic Acid ◽  
Proof Of Concept ◽  
Critical Bone Defects

Bone regenerative medicine (BRM) aims to overcome the limitations of conventional treatments for critical bone defects by developing therapeutic strategies, based on temporary bioactive substitutes, capable of stimulating, sustaining, and guiding tissue regeneration. The aim of this study was to validate the “proof of concept” of a cellularized bioactive scaffold and establish its potential for use in BRM. For this purpose, three-dimensional scaffolds of poly-(lactic acid) (PLA), produced by the additive manufacturing technique, were incorporated into a human platelet-rich plasma (PRP-h) fibrin matrix containing human infrapatellar fat pad mesenchymal stem cells (hIFPMSC). The scaffolds (PLA/finbrin-bioactive) were kept under ideal culture conditions in a medium free from fetal bovine serum and analyzed at 5 and 10 days by Scanning Electron Microscopy (SEM), Fourrier Transform Infrared (FTIR), Circular Dichroism and fluorescence microscopy. The results demonstrated the feasibility of obtaining a rigid, cytocompatible, and cellularized three-dimensional structure. In addition, PRP platelets and leukocytes were able to provide a bioactive environment capable of maintaining the viability of hIFPMSC into scaffolds. The results validate the concept of a customizable, bioactive, cellularized, and non-immunogenic strategy for application in BRM.

scholarly journals Study of Mini Channel Heat Sink with Different Internal Configuration

2020 ◽  
Vol 319 ◽  
pp. 02004
Author(s):  
Muhammad Akif Rahman ◽  
Md Badrath Tamam ◽  
Md Sadman Faruque ◽  
A.K.M. Monjur Morshed
Keyword(s):  
Nusselt Number ◽  
Thermal Performance ◽  
Heat Sink ◽  
Rectangular Channel ◽  
Three Dimensional ◽  
Heat Sinks ◽  
Maximum Temperature ◽  
Rectangular Channels ◽  
Flow Through ◽  
Internal Configuration

In this paper a numerical analysis of three-dimensional laminar flow through rectangular channel heat sinks of different geometric configuration is presented and a comparison of thermal performance among the heat sinks is discussed. Liquid water was used as coolant in the aluminum made heat sink with a glass cover above it. The aspect ratio (section height to width) of rectangular channels of the mini-channel heat sink was 0.33. A heat flux of 20 W/cm2 was continuously applied at the bottom of the channel with different inlet velocity for Reynold’s number ranging from 150 to 1044. Interconnectors and obstacles at different positions and numbers inside the channel were introduced in order to enhance the thermal performance. These modifications cause secondary flow between the parallel channels and the obstacles disrupt the boundary layer formation of the flow inside the channel which leads to the increase in heat transfer rate. Finally, Nusselt number, overall thermal resistance and maximum temperature of the heat sink were calculated to compare the performances of the modified heat sinks with the conventional mini channel heat sink and it was observed that the heat sink with both interconnectors and obstacles enhanced the thermal performance more significantly than other configurations. A maximum of 36% increase in Nusselt number was observed (for Re =1044).

A Three-Dimensional Viscous Transonic Inverse Design Method

2000 ◽  
Author(s):  
W. T. Tiow ◽  
M. Zangeneh
Keyword(s):  
Design Method ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Viscous Effects ◽  
Flow Equations ◽  
Flow Solution ◽  
Turbomachinery Blades ◽  
A Cell ◽  
Inverse Design Method ◽  
Euler Solver

The development and application of a three-dimensional inverse methodology is presented for the design of turbomachinery blades. The method is based on the mass-averaged swirl, rV~θ distribution and computes the necessary blade changes directly from the discrepancies between the target and initial distributions. The flow solution and blade modification converge simultaneously giving the final blade geometry and the corresponding steady state flow solution. The flow analysis is performed using a cell-vertex finite volume time-marching algorithm employing the multistage Runge-Kutta integrator in conjunction with accelerating techniques (local time stepping and grid sequencing). To account for viscous effects, dissipative forces are included in the Euler solver using the log-law and mixing length models. The design method can be used with any existing solver solving the same flow equations without any modifications to the blade surface wall boundary condition. Validation of the method has been carried out using a transonic annular turbine nozzle and NASA rotor 67. Finally, the method is demonstrated on the re-design of the blades.

scholarly journals Computation of Three-Dimensional, Rotational Flow Through Turbomachinery Blade Rows for Improved Aerodynamic Design Studies

1986 ◽  
Author(s):  
S. V. Subramanian ◽  
R. Bozzola ◽  
Louis A. Povinelli
Keyword(s):  
Three Dimensional ◽  
Maximum Flow ◽  
Cost Effective ◽  
Computer Code ◽  
Integration Scheme ◽  
Aerodynamic Design ◽  
Design Studies ◽  
Flow Equations ◽  
Transonic Compressor ◽  
Numerical Predictions

The performance of a three dimensional computer code developed for predicting the flowfield in stationary and rotating turbomachinery blade rows is described in this study. The four stage Runge-Kutta numerical integration scheme is used for solving the governing flow equations and yields solution to the full, three dimensional, unsteady Euler equations in cylindrical coordinates. This method is fully explicit and uses the finite volume, time marching procedure. In order to demonstrate the accuracy and efficiency of the code, steady solutions were obtained for several cascade geometries under widely varying flow conditions. Computed flowfield results are presented for a fully subsonic turbine stator and a low aspect ratio, transonic compressor rotor blade under maximum flow and peak efficiency design conditions. Comparisons with Laser Anemometer measurements and other numerical predictions are also provided to illustrate that the present method predicts important flow features with good accuracy and can be used for cost effective aerodynamic design studies.

Influence of a Honeycomb Facing on the Flow Through a Stepped Labyrinth Seal

2000 ◽  
Vol 124 (1) ◽  
pp. 140-146 ◽  
Author(s):  
V. Schramm ◽  
K. Willenborg ◽  
S. Kim ◽  
S. Wittig
Keyword(s):  
Flow Field ◽  
Three Dimensional ◽  
Theoretical Work ◽  
Labyrinth Seal ◽  
Honeycomb Structure ◽  
Experimental Investigations ◽  
Labyrinth Seals ◽  
Numerical Predictions ◽  
Flow Through ◽  
Aero Engines

This paper reports numerical predictions and measurements of the flow field in a stepped labyrinth seal. The theoretical work and the experimental investigations were successfully combined to gain a comprehensive understanding of the flow patterns existing in such elements. In order to identify the influence of the honeycomb structure, a smooth stator as well as a seal configuration with a honeycomb facing mounted on the stator wall were investigated. The seal geometry is representative of typical three-step labyrinth seals of modern aero engines. The flow field was predicted using a commercial finite volume code with the standard k-ε turbulence model. The computational grid includes the basic seal geometry as well as the three-dimensional honeycomb structures.

Numerical Simulation for Flow Through Conducting Metal and Metallic Oxide Nanofluids

2020 ◽  
Vol 9 (4) ◽  
pp. 354-361
Author(s):  
P. K. Pattnaik ◽  
S. R. Mishra ◽  
Ram Prakash Sharma
Keyword(s):  
Metal Oxide Nanoparticles ◽  
Three Dimensional ◽  
Adomian Decomposition Method ◽  
Metallic Oxide ◽  
Electrically Conducting ◽  
Number Comparison ◽  
Adomian Decomposition ◽  
Flow Through ◽  
Analytical Result ◽  
Exponentially Stretching

Present paper aims to analyze three-dimensional (3D) motion of an electrically conducting nanofluid past an exponentially stretching sheet. Both metal and metal oxide nanoparticles (such as Cu, Al2O3, TiO2) in the base fluid (water) are examined. Nonlinear ordinary differential systems are obtained by suitable transformations. The crux of the analysis is the development of an estimated analytical result obtained by employing the “Adomian Decomposition Method” (ADM), an approximate analytical method. Momentum and energy descriptions with prescribed boundary conditions are employed. The velocity components and temperature are analyzed. Tabulated values are organized aimed at the outcomes of skin-friction coefficients and Nusselt number. Comparison with past limiting results is shown. Finally, the outstanding outcomes of the present result are; the velocity profile with the inclusion of particle concentration and magnetic parameter decelerate significantly and Al2O3 nanoparticles are favorable for the enhancement in the rate of heat transfer.

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