Horizontal Wall Movement and Ground Surface Settlement Analysis of Braced Excavation Based on Support Spacing

Lateral supports, including walls and bracing systems on deep excavation, are generally required to prevent excessive horizontal wall movement and ground surface settlement which can cause damage to the excavation construction itself and adjacent structures. These criteria are influenced by the stiffness of the excavation system, including the spacing of vertical and horizontal supports (struts). This paper presents the parametric study using the variation of struts spacing in the vertical and horizontal direction to analyze the influence on horizontal wall movement and ground surface settlement. The analysis was carried out using finite element software, PLAXIS performed in 2D plain strain and 3D. This study shows that struts spacing in the horizontal and vertical direction is equally important and equally significant on the deformation that occurs with a maximum difference of about 0.06%. The maximum horizontal wall movement ratio computed by 3D analysis to the 2D analysis is defined as plain strain ratio (PSR). The PSR value decreases when the system stiffness is decreased. Meanwhile, when the system stiffness was higher, the PSR value will be higher and closer to 1, showing that the difference in the 3D and 2D models is relatively small.

Mixed Convection in a Double Lid-Driven Cavity Filled with Hybrid Nanofluid by Using Finite Volume Method

The understanding of mixed convection heat transfer in cavity is crucial for studying the energy consumption and efficiency in many engineering devices. In the present work, the hybrid nanofluid (Al2O3-Cu-Water) is employed to increase the heat transfer rate in a double lid-driven rectangular cavity. The bottom movable horizontal wall is kept at a high temperature while the top movable horizontal wall is kept at a low temperature. The sidewalls are insulated. The mass, momentum and energy equations are numerically solved using the Finite Volume Method (FVM). The SIMPLE algorithm is used for pressure-velocity coupling. Parameters such as Reynold’s number (Re), Richardson number (Ri), moving wall direction, solid volume fraction, and cavity length are studied. The results show that the hybrid nanofluid in the rectangular cavity is able to augment the heat transfer significantly. When Re is high, a big size solid body can augment the heat transfer. Heat transfer increases with respect to Ri. Meanwhile, the local Nusselt number decreases with respect to the cavity length.

Effects of wall proximity on the airflow in a vertical solar chimney for natural ventilation of dwellings

This study investigates performance of a vertical solar chimney, which absorbs solar energy and induces airflow for natural ventilation and cooling of dwellings, under effects of walls neighboring to its air channel. A computational fluid dynamics model was developed to predict induced flow rate and thermal efficiency of a vertical solar chimney with four types of nearby walls: a vertical wall to which the solar chimney was attached, a horizontal plate above the outlet of the air channel, a horizontal plate, and a horizontal wall below the inlet of the air channel. Examined factors included the heat flux in the air channel, the chimney height, the air gap, the distance of the walls, and the location of the heat source in the air channel. The results showed that effects of the wall proximity were modulated by the location of the heat source and the ratio G/ H between the air gap and the chimney height. Particularly, performance of the chimney was enhanced when the heat source was on the opposite side of the vertical wall and when G/ H was large.

Effect of Inclination and of Darcy Number on Bifurcations and Thermal Transfer in a Square Porous Cavity

In the present work a numerical study of natural convection in air in a square cavity filled with a porous media, was carried out in order to analyze the effects of the inclination angle and the Darcy number on the roads toward the chaos. The horizontal wall of the cavity is adiabatic while the vertical walls, composed of two part of the same size, are maintained at different temperatures. The dimensionless transfer equations, expressed in terms of stream function and vorticity had been solved using the Alternating Direction Implicit Method (ADI) and the GAUSS elimination method. The different bifurcations had been represented by attractor in phase space and by amplitude spectrum. We have noticed that for an inclination angle equal to 30°, the scenario of the roads towards the chaos is in agreement with the one of Feigen Baum. For the inclination angle equal to 60°, the scenario is that of Ruelle and Takens which is by quasi periodicity.

Effect of finite wall thickness on entropy generation and natural convection in a nanofluid-filled partially heated square cavity

Purpose The purpose of this paper is to study the effects of finite wall thickness on the natural convection and entropy generation in a square cavity filled with Al2O3–water nanofluid in the presence of bottom heat source. Design/methodology/approach The moving isothermal heater was placed on the bottom solid wall. The vertical walls (left and right walls) were fully maintained at low temperatures. The rest of the bottom solid wall along with the top horizontal wall was kept adiabatic. The boundaries of the domain are assumed to be impermeable; the fluid within the cavity is a water-based nanofluid having Al2O3 nanoparticles. The Boussinesq approximation is applicable. The dimensionless governing equations subject to the selected boundary conditions are solved using the finite difference method. The current proposed numerical method is proven excellent through comparisons with the existing experimental and numerical published studies. Findings Numerical results were demonstrated graphically in several forms including streamlines, isotherms and local entropy generation, as well as the local and average Nusselt numbers. The results reveal that the thermal conductivity and thickness of the solid wall are important control parameters for optimization of heat transfer and Bejan number within the partially heated square cavity. Originality/value According to the past research studies mentioned above and to the best of the authors’ knowledge, the gap regarding the problem with entropy generation analysis and natural convection in partially heated square cavity has yet to be filled. Because of this, this study aims to investigate the entropy generation analysis as well as the natural convection in nanofluid-filled square cavity which was heated partially. A square cavity with an isothermal heater located on the bottom solid horizontal wall of the cavity and partly cold sidewalls are essential problems in thermal processing applications. Hence, the authors believe that this present work will be a valuable contribution in improving the thermal performance.

Effects of two-phase nanofluid model on convection in a double lid-driven cavity in the presence of a magnetic field

Purpose The aim of this study is to investigate the effects of two-phase nanofluid model on mixed convection in a double lid-driven square cavity in the presence of a magnetic field. The authors believe that this work is a good contribution for improving the thermal performance and the heat transfer enhancement in some engineering instruments. Design/methodology/approach The current work investigates the problem of mixed convection heat transfer in a double lid-driven square cavity in the presence of magnetic field. The used cavity is filled with water-Al2O3 nanofluid based on Buongiorno’s two-phase model. The bottom horizontal wall is maintained at a constant high temperature and moves to the left/right, while the top horizontal wall is maintained at a constant low temperature and moves to the right/left. The left and right vertical walls are thermally insulated. The dimensionless governing equations are solved numerically using the Galerkin weighted residual finite element method. Findings The obtained results show that the heat transfer rate enhances with an increment of Reynolds number or a reduction of Hartmann number. In addition, effects of thermophoresis and Brownian motion play a significant role in the growth of convection heat transfer. Originality/value According to above-mentioned studies and to the authors’ best knowledge, there has no study reported the MHD mixed convection heat transfer in a double lid-driven cavity using the two-phase nanofluid model. Thus, the authors of the present study believe that this work is valuable. Therefore, the aim of this comprehensive numerical study is to investigate the effects of two-phase nanofluid model on mixed convection in a double lid-driven square cavity in the presence of a magnetic field. The authors believe that this work is a good contribution for improving the thermal performance and the heat transfer enhancement in some engineering instruments.

Architectural Typology of the Malay Chinatown Facade

Chinatown architecture in Bagansiapiapi is a major component of the Chinatown area as an identity with various facades influenced by local Malay culture. The growth and development of cities with economic orientation is often not in line with the understanding to maintain the image of the building, which has an impact on district transformation which can eliminate the existence of Chinatown architecture that currently exists or intersects with the city Commercial center. This can be seen in the changes in facade formation that took place on the Bagansiapiapi Perniagaan street. The typology of facade architecture of the Chinatown building was carried out with the aim of (i)Knowing the character of the facade shape of Chinatown facade, (ii)Getting the dominant formation in each of the facade forming element , so that Chinatown buildings can still be found. The method used is a qualitative method with a descriptive approach, which is directed at describing and interpreting existing conditions. The analysis used by classifying facades on elements of Malay Chinatown architecture includes types of building dimensions, ownership and function modules, which are formed by facade components (roofs, vents, doors, windows, walls, and stilt construction). The findings of this study are the facade of the Chinatown building in Bagansiapiapi on the facade of formation elements that have dominance: 1) Module composition of the core dimensions (a) 1 function of the house floor with wood 2) The shape of the gable, the formation of plain rectangular windows and two long ornaments downward, the formation of the window extends downward by placing a balanced composition right and left, setting a horizontal wall, using a stilt construction. Keyword: Architecture of Chinatown, Facade Elements, Malay Architecture, Typology