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CFD-based simulation of dense gas dispersion in presence of obstacles
, Article Journal of Loss Prevention in the Process Industries ; Volume 24, Issue 4 , 2011 , Pages 371-376 ; 09504230 (ISSN) ; Rashtchian, D ; Abbasi, S. A ; Sharif University of Technology
2011
Abstract
Quantification of spatial and temporal concentration profiles of vapor clouds resulting from accidental loss of containment of toxic and/or flammable substances is of great importance as correct prediction of spatial and temporal profiles can not only help in designing mitigation/prevention equipment such as gas detection alarms and shutdown procedures but also help decide on modifications that may help prevent any escalation of the event. The most commonly used models - SLAB (Ermak, 1990), HEGADAS (Colenbrander, 1980), DEGADIS (Spicer & Havens, 1989), HGSYSTEM (Witlox & McFarlane, 1994), PHAST (DNV, 2007), ALOHA (EPA & NOAA, 2007), SCIPUFF (Sykes, Parker, Henn, & Chowdhury, 2007), TRACE...
Investigation of Plasticizing and Slump Retaining Properties of
PEG-Based Tri-Block Copolymers in Cementitious Systems
,
M.Sc. Thesis
Sharif University of Technology
;
Pourjavadi, Ali
(Supervisor)
Abstract
Plasticizers in cementitious systems are additives that upon addition at a low dosage can change the workability, mechanical strength and other properties of cement paste effectively. In this study, tri-block copolymers based on poly ethylene glycol (PEG) was synthesised and their applications in the cementitious systems investigated. The main purpose is the verification of plasticizing effects of these copolymers in the cement paste. ABA tri-block copolymers with PEG (1000 and 1500 g/mol) as B block, poly caprolactone, poly caprolactam, poly lactide and poly glycolide (with different weight ratio) as A block were synthesised via ring opening polymerization with stannous octanoate as...
An investigation on the effect of cement and silica fume on properties of self-compacting concrete
, Article Proceedings of the 13th East Asia-Pacific Conference on Structural Engineering and Construction, EASEC 2013 ; September , 2013 ; Atashnama, A ; Panahi, M ; Gharebaghi, R ; Mahlouji, J ; Sharif University of Technology
Hokkaido University collection of Scholarly Academic Papers, HUSCAP
2013
Abstract
Self-Compacting concrete (SCC) is identified as a high performance concrete with the ability of self compaction, using its own weight without any external vibration. SCC is able to fill congested area and voids, even in highly reinforced concrete members whilst it flows without segregation. The fresh properties of SCC such as workability can be determined using different tests including slump-flow, J ring, V-funnel, U box, L box, GTM and column technique. In this paper the effect of different amount of cementitious material, silica fume and W/C ratios on workability and compressive strength of SCC are investigated. The results indicate that the workability of mixtures is reduced by...
URANS simulation of 2D continuous and discontinuous gravity currents
, Article Journal of Applied Sciences ; Volume 8, Issue 16 , 2008 , Pages 2801-2813 ; 18125654 (ISSN) ; Namin, M. M ; Salehi, A. A ; Firoozabadi, B ; Javan, M ; Sharif University of Technology
2008
Abstract
This study seeks to explore the ability of unsteady Reynolds-averaged Navier-Stokes (URANS) simulation approach for resolving two-dimensional (2D) gravity currents on fine computational meshes. A 2D URANS equations closed by a buoyancy-modified k-ε turbulence model are integrated in time with a second-order fractional step approach coupled with a direct implicit method and discretized in space on a staggered mesh using a second-order accurate finite volume approach incorporating a high resolution semi-Lagrangian technique for the convective terms. A series of 2D simulations are carried out for gravity currents from both discontinuous and continuous sources. Comparisons with experimental...