scholarly journals Erratum for “Numerical Study for Evaluating the Effect of Length-to-Height Ratio on the Behavior of Concrete Frame Retrofitted with Steel Infill Plates” by Reza Kamgar and Mohammad Reza Babadaei Samani

2022 ◽  
Vol 27 (1) ◽  
Author(s):  
Reza Kamgar ◽  
Mohammad Reza Babadaei Samani
Keyword(s):  
Numerical Study ◽  
Height Ratio ◽  
Concrete Frame

NUMERICAL STUDY OF LAMINAR CONVECTION AND THERMOSOLUTAL CONVECTION IN A TWO-DIMENSIONAL TRAPEZOIDAL CAVITY

1994 ◽  
Vol 18 (3) ◽  
pp. 207-224 ◽  
Author(s):  
M. Lacroix
Keyword(s):  
Schmidt Number ◽  
Numerical Study ◽  
Temperature Gradients ◽  
Thermosolutal Convection ◽  
Governing Equations ◽  
Concentration Gradients ◽  
Height Ratio ◽  
Vertical Walls ◽  
Laminar Convection ◽  
Rayleigh Numbers

Heat transfer driven by temperature gradients and simultaneous temperature and concentration gradients has been studied numerically for horizontal prismatic cavities of trapezoidal section having a hot horizontal base, a cool inclined top and insulated vertical walls. Results are presented for a cavity with width-to-mean height ratio of 4, thermal and concentration Rayleigh numbers up to 106 and 5.105 respectively, and top surface inclinations from 0 to 15 deg to the horizontal. The Prandtl and the Schmidt number used are 0.71 and 0.6 respectively. The governing equations are expressed in terms of stream function and vorticity and body-fitted coordinates are used for mapping the sloping top wall. As the inclination of the top surface is increased, the Nusselt and Sherwood numbers decrease. The effect of opposing thermal and concentration gradients on the Nusselt and Sherwood numbers is however more important than the effect of the inclination of the top surface. Theoretical Nusselt and Sherwood numbers are compared with available experimental data.

Laminar Convective Heat Transfer in a Microchannel With Internal Fins

2008 ◽  
Author(s):  
Ramesh Narayanaswamy ◽  
Tilak T. Chandratilleke ◽  
Andrew J. L. Foong
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Constant Heat Flux ◽  
Channel Length ◽  
Height Ratio ◽  
Flux Boundary Conditions ◽  
Nusselt Number Distribution ◽  
Internal Fins ◽  
Square Microchannel

A numerical study was conducted to investigate the fluid flow and heat transfer characteristics of a square microchannel with four longitudinal internal fins. Three-dimensional numerical simulations were performed on the microchannel with variable fin height ratio in the presence of a hydrodynamically developed, thermally developing laminar flow. Constant heat flux boundary conditions were assumed on the external walls of the square microchannel. Results of local Nusselt number distribution along the channel length were obtained as a function of the fin height ratio. The analysis was carried out for different fin heights and flow parameters. Interesting observations that provide more physical insight on this passive enhancement technique, and the existence of an optimum fin height is brought out in the present study.

scholarly journals Experimental and Numerical Study of Seismic Performance of Precast Prestressed Concrete Frame Internal Connection

2015 ◽  
pp. 406-413
Author(s):  
Xiandong Liao ◽  
Xiang Hu
Keyword(s):  
Seismic Performance ◽  
Prestressed Concrete ◽  
Carrying Capacity ◽  
Numerical Study ◽  
Scale Model ◽  
Load Carrying Capacity ◽  
Concrete Frame ◽  
Internal Connection ◽  
Load Carrying ◽  
Precast Prestressed Concrete

The seismic performance of the internal connection of precast prestressed concrete frame was studied systematically, based on the experiment of full-scale model under low cyclic reversed loading. This study was mainly focused on failure pattern, load-carrying capacity, skeleton curves, and hysteresis curves. Furthermore, a nonlinear finite element analysis using Abaqus was carried out to study the characteristics of the internal connection of precast prestressed concrete frame. Results revealed that the damage was concentrated mainly on beam end owing to flexural action, while steel bars in the columns and stirrups in the core region remained elastic until failure occurred. The calculated value of the load-carrying capacity of the internal connection was similar to the experimental one. Present study can be referenced for the application of precast prestressed concrete frame in high seismic zones.

scholarly journals A Relative Reliability Approach for Direct Displacement-Based Seismic Design of Partially Prestressed Reinforced Concrete Frame Structures

2015 ◽  
Vol 2015 ◽  
pp. 1-10
Author(s):  
Bin Jian ◽  
Chaoyi Lei ◽  
Pingping Liao
Keyword(s):  
Reinforced Concrete ◽  
Numerical Study ◽  
Frame Structures ◽  
Risk Level ◽  
Earthquake Risk ◽  
Base Shear ◽  
Reinforced Concrete Frame ◽  
Relative Reliability ◽  
Concrete Frame ◽  
Displacement Based

A relative reliability approach for Direct Displacement-Based Design (DDBD) is first proposed in this paper, which is based on the average reliability level implicit in current Chinese design codes. By introducing a relative reliability coefficientα, the determination of reliability from DDBD is transformed to the calculation of its ratio to the average reliability of current Chinese codes. This approach not only follows the reliability principle of current Chinese codes, but also avoids the complex calculation of reliability in general. The calculation of reliability at any performance level can be transformed to the nominal reliability of frequent earthquake for the expected earthquake risk level. Meanwhile, based on the assumption of elasticity, it is shown that, under frequent earthquake risk, the calculated base shear derived from DDBD theoretically equals that from force-based design (FBD). Therefore, a revised calculation of section bearing capacity for DDBD, which follows the expression in current Chinese codes, is advised, according to the numerical study of 24 examples of Partially Prestressed Reinforced Concrete (PPRC) frame structures. Finally, this proposed approach is verified to be effective and superior by a comparative analysis of 10 examples of PPRC frames.

Efficient Robust Optimization of Structures Subjected to Earthquake Load and Characterized by Uncertain Bounded System Parameters

2012 ◽  
pp. 105-127
Author(s):  
Subrata Chakraborty ◽  
Soumya Bhattacharjya
Keyword(s):  
Numerical Study ◽  
Frame Structure ◽  
Robust Design Optimization ◽  
Computational Time ◽  
System Parameters ◽  
Concrete Frame ◽  
Earthquake Load ◽  
Time Requirements ◽  
Adaptive Response Surface Method ◽  
Bounded System

An efficient robust design optimization (RDO) procedure is proposed in the framework of an adaptive response surface method (RSM) for structures subjected to earthquake load and characterized by uncertain but bounded system parameters. The basic idea of the proposed RDO approach is to improve the robustness of a design by using a new dispersion index which utilizes the relative importance of the gradients of the performance function. The same concept is also applied to the constraints. The repeated computations of stochastic responses and their sensitivities for evaluating the stochastic constraint of the associated optimization problem are efficiently obtained in the framework of an adaptive RSM. The proposed RDO approach is elucidated through the optimization of a three-storied concrete frame structure. The numerical study depicts that the proposed RDO results are in conformity with the conventional RDO results. However, definite improvements are achieved in terms of robustness and computational time requirements indicating its efficiency over the conventional RDO approach.

Numerical Study on Heat Transfer Enhancement of Swirl Chamber on Gas Turbine Blade

2018 ◽  
Vol 35 (4) ◽  
pp. 403-412 ◽  
Author(s):  
Haifen Du ◽  
Daimei Xie ◽  
Wei Jiang ◽  
Tong Chen ◽  
Jianshu Gao
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Gas Turbine ◽  
Numerical Study ◽  
Transfer Effect ◽  
Research Field ◽  
Temperature Ratio ◽  
Height Ratio ◽  
Swirl Chamber

Abstract The optimization of turbine cooling design has become a new research field of gas turbine. The swirl chamber is a prospect cooling concept. In this paper, the numerical simulation of the swirl chamber is carried out by FLUENT. The influence of inlet size parameters, temperature ratio and inlet Reynolds number on the enhanced heat transfer of swirl chamber is studied. The results show that, in the range of the studied condition, Nusselt number decreases with the height, the width, the ratio of width to height and Reynolds number. It also shows that comprehensive heat transfer effect is best at d=20 mm and enhances observably with the enlargement of width, width height ratio, and Reynolds number. Friction factor increases with height, width, temperature ratio and Reynolds number decreases. It is increased by increasing width height ratio. Nusselt number and comprehensive heat transfer effect decrease a little with aggrandizement of temperature ratio.

scholarly journals Experimental and numerical study on the thrust of a water-retaining curtain

2017 ◽  
Vol 20 (2) ◽  
pp. 316-331 ◽  
Author(s):  
Wei He ◽  
Jijian Lian ◽  
Fang Liu ◽  
Chao Ma ◽  
Shunqi Pan
Keyword(s):  
Pressure Difference ◽  
Numerical Study ◽  
Experimental Tests ◽  
Maximum Pressure ◽  
Arc Length ◽  
Practical Application ◽  
Force Analysis ◽  
Height Ratio ◽  
Maximum Value ◽  
Inflow Condition

Abstract A water-retaining curtain (WRC) has become a useful facility in selective withdrawal and sedimentation control, but the force analysis of a curved curtain is still lacking. Based on flume experimental tests and numerical simulations, this paper analyzes the variation laws of pressure difference and thrust of WRC. The results show that under the uniform inflow condition, the distribution of pressure difference on the WRC is relatively even, and the maximum value is located at the upper part of the curtain. When arc length–height ratio increases, the location of maximum pressure difference gets lower. In addition, the variation law of thrust of WRC conforms to the classical resistance equation. The drag coefficient is found to fit a power function of the water-retaining ratio, a second-degree polynomial function of arc length–height ratio, and linear function of inclination ratio. The results also yield a simplified forecasting formula of thrust of WRC which is proposed and verified using flume simulations and a real reservoir model test. The newly developed formula systematically considers the water-retaining height, arc length and inclination degree, providing a rapid and accurate algorithm to predict the thrust, and lays a theoretical foundation for practical application.

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