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Continuous solid-state fermentation as affected by substrate flow pattern
, Article Chemical Engineering Science ; Volume 61, Issue 8 , 2006 , Pages 2675-2687 ; 00092509 (ISSN) ; Mitchell, D. A ; Beheshti, M ; Roostaazad, R ; Sánchez, L. R ; Sharif University of Technology
2006
Abstract
The performance of continuous solid state bioreactors having two different solid substrate flow patterns, namely plug flow and completely mixed flow, is quantified for both steady-state and transient operation using a simple mathematical model. The core assumption is that each substrate particle acts as an infinitesimal bioreactor. The residence time distribution of the particles is considered in the formulation of the equations for the mixed-flow bioreactor and the error that results from neglecting it is investigated by comparing the simulation results with those of a completely mixed, continuous bioreactor for submerged liquid fermentation (a chemostat). The model is extended to include...
Liquid flow analysis in concentric annular heat pipes wicks
, Article Journal of Porous Media ; Volume 8, Issue 5 , 2005 , Pages 471-480 ; 1091028X (ISSN) ; Layeghi, M ; Sharif University of Technology
2005
Abstract
In this paper, two models are developed to predict liquid pressure drop and velocity profile in the wicks of concentric annular heat pipes. A steady-state incompressible laminar flow is modeled in the wicks based on velocity and pressure mean values by the extended Darcy-Brinkman model. The corresponding one- and two-dimensional governing equations are solved analytically and numerically, respectively, in the range of low to moderate radial Reynolds numbers. It has been found that there is a difference, about 12% in the worse case, between the total pressure drops of the two models. Whereas, the predicted total pressure drop by the one-dimensional model and that of the Darcy model are in...
A novel mechanism for heat transfer enhancement through microchannels using electrokinetic effect
, Article 2005 ASME Summer Heat Transfer Conference, HT 2005, San Francisco, CA, 17 July 2005 through 22 July 2005 ; Volume 3 , 2005 , Pages 949-955 ; 0791847314 (ISBN); 9780791847312 (ISBN) ; Manzari, M. T ; Monazami, R ; Bazargan, V ; Sharif University of Technology
2005
Abstract
In this paper a three-dimensional numerical model is developed in order to study the heat transfer enhancement in rectangular microchannels due to electrokinetic effect. The electrokinetic body force on fluid elements gives some superior convective transport properties to the flow relative to pure pressure driven flow in microchannels. Unlike the conventional parabolic velocity profile of pressure driven laminar flow, the electrokinetic body force transforms the velocity profile to a slug-like flow. Due to sharp velocity gradient near the wall, the convective heat transfer properties of the flow are improved dramatically. Net charge distribution across the channel is obtained by solving the...
Analysis of fluid flow and heat transfer in microchannels using combined pressure gradient and electroosmotic pumping
, Article 3rd International Conference on Microchannels and Minichannels, ICMM2005, Toronto, ON, 13 June 2005 through 15 June 2005 ; Volume PART A , 2005 , Pages 503-510 ; 0791841855 (ISBN) ; Zade, A. Q ; Manzari, M. T ; Sharif University of Technology
2005
Abstract
A numerical model has been developed for studying the flow and heat transfer characteristics of single phase liquid flow through a microchannel. In this work the heat transfer characteristics of pressure driven and electroosmotic flow through microchannels have been studied. The governing equations are the Poisson-Boltzmann and Navier-Stokes equations which have been solved numerically using the standard Galerkin and the Mixed 4-1 finite element methods, respectively. Finally the energy equation is solved numerically using the Stream-wise Upwind Petrov Galerkin (SUPG) method. Two dimensional Poisson-Boltzmann equation was first solved to find the electric potential field and net charge...
Experimental results of pressure variation in two-phase air-water flow in water tunnels
, Article 31st IAHR Congress 2005: Water Engineering for the Future, Choices and Challenges, 11 September 2005 through 16 September 2005 ; 2005 , Pages 6523-6533 ; 8987898245 (ISBN); 9788987898247 (ISBN) ; Byong-Ho J ; Sang I. L ; Won S. I ; Gye-Woon C ; Sharif University of Technology
Korea Water Resources Association
2005
Abstract
An experimental investigation has been carried out to verify characteristics of pressure fluctuations inside a circular, horizontal and inclined pipeline (90mm inside diameter and 10 m long) carrying two-phase air-water flow in a controlled manner (operating at room temperature and normal pressure). The pressure fluctuation was considered to be due to interaction between the fluid and air bubble compressibility in the pipe. The fluctuating pressure was studied in detail while the flow pattern was mainly slug, wavy or stratified flow. The tests were carried out varying with time, space, water flow rate/air flow rate ratio and pipe inclination. The pressure fluctuations were measured...
Fractal behaviour of flow of inhomogeneous fluids over smooth inclined surfaces
, Article Journal of Physics Condensed Matter ; Volume 16, Issue 15 , 2004 , Pages 2497-2505 ; 09538984 (ISSN) ; Ghane Motlagh, B ; Baradaran, S ; Shekarian, E ; Rouhani, S ; Sharif University of Technology
2004
Abstract
Patterns formed by the flow of an inhomogeneous fluid (suspension) over a smooth inclined surface were studied. It was observed that fractal patterns form. There exists a threshold angle for the inclination above which global fractal patterns are formed. This angle depends on the particle size of the suspension. We observed that there are two fractal dimensions for these patterns, depending on the area from which the pattern is extracted. If the pattern is taken from the top which only consists of the beginning steps of the pattern forming, one finds two fractal dimensions, i.e. 1.35-1.45 and 1.6-1.7, in which the first one is dominant while, if the entire pattern is taken, then a fractal...
A Study on Two-Phase Flow in Bottom Hole Conditions in Horizontal Wells
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor)
Abstract
Considering the importance of oil and gas industries in Iran, issues related to drilling and exploitation of oil and gas fields are among the country's priorities and challenges in industries, research centers and universities, and extensive research is conducted in this field. Since during the process of oil production from oil wells and reservoirs, the formation of multiphase flows, including two-phase fluid flow, is inevitable, investigating the behavior of multiphase fluids, which is a branch of fluid mechanics, is of special importance. In this regard, in continuation of the research conducted in the Faculty of Chemical and Petroleum Engineering of Sharif University of Technology, in...
Production Well Multi-Phase Flow Measurement Using Ultrasonic Technology
, M.Sc. Thesis Sharif University of Technology ; Taghikhani, Vahid (Supervisor) ; Sahd, Saeed (Supervisor) ; Amjadi, Ahmad (Co-Supervisor)
Abstract
Flow measurement in both types of single phase and multiphase has a crucial place in a wide variety of industries, specially petroleum industry. for single phase flowmeters, improving their precision using different types of mechanical, mathematical and analytical techniques will be considered as an important step. Using multiphase flow meters will cause no need of volume catching and costly separators and also make us capable of taking well-timed decisions in production management. for making flow meters weather multiphase or single phase, there is a crucial need of a multiphase flow loop. To achieve that, an 8-meter-long flow loop using transparent Plexiglas pipes with inside diameter of...
Experimental Study of the Effect of Interaction of Two Flexible Stems on Diffusion of the Contamination
, M.Sc. Thesis Sharif University of Technology ; Jamali, Mirmosadegh (Supervisor)
Abstract
In this research, the dynamic of flow, dispersion of contaminant and characteristic of wake in the presence of two flexible stems of polyurethane is investigated in a hydraulic flume. The stream velocity of 2.28, 4.47 and 7.58 cm/s are considered, which are equivalent to Reynolds number in stem diameter scale 173, 340 and 576. The spacing ratio of two stems are one, two and three in both transverse and longitudinal direction. Velocity fields are measured using Particle Image Velocimetry (PIV) technique. The size of wake area behind stems is determined using the flow field measurement. The results show that the spacing ratio l/d affects the wake area size and interactions of wakes. The...
Liquid-Liquid Two Phase Flow in Horizontal Well on Bottom Hole Condition: Creation a Visualized Flow Regime for Two Phase (Liquid-liquid) Flow
, M.Sc. Thesis Sharif University of Technology ; Ghoodarznia, Iraj (Supervisor)
Abstract
The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between viscous, gravity and capillary forces. Due to the fact that the dominant forces vary for different flow regimes, the pressure...
Experimental Investigation and CFD Simulation of the Flow Pattern of the FCC's Fluidized Bed Regenerator
, M.Sc. Thesis Sharif University of Technology ; Dehkordi, Asghar Molaei (Supervisor) ; Seifkordi, Aliakbar (Supervisor) ; Behjat, Yaghoub (Supervisor)
Abstract
Hydrodynamic behavior of gas-solid fluidization in large-diameter beds like FCC regenerator exhibits complex aspects. To investigate the gas-solid flow pattern of UOP's combustor-style FCC regenerator, a lab-scale regenerator was designed by a downscale factor of 0.045. The regenerator's operation and fluidization of FCC particles through it was examined and pressure axial distributions were measured and analyzed at different superficial air velocities. 3D CFD simulation of the regenerator was performed with Eulerian-Eulerian approach to investigate the effects of operating conditions, including superficial air velocity, catalyst mass flux, presence of recirculated catalyst, and the...
Investigation of Multiphase Flow in Oil Wells (with Focus on Two Phase Flow), Flow Pattern Recognition and Modeling
, M.Sc. Thesis Sharif University of Technology ; Shad, Saeed (Supervisor) ; Jamshidi, Saeed (Supervisor)
Abstract
The concurrent flow of oil and water is a common occurrence in the field of multiphase flow in different fields including petroleum industry. In oil and gas, production engineers often face a situation in which more than one phase is flowing through the producers. In such conditions an accurate assessment of pressure loss inside the well plays a vital role in efficient and effective production planning. Changes in well orientation, wellbore diameter, reservoir and fluid properties as well as fluid flow rates are among parameters in which will affect the flow patterns that can occur inside a well during its life time. These flow patterns are created as a result of a competition between...
Numerical Simulation and Manufacture of a Proton Exchange Membrane Fuel Cell to Examine Mass and Charge Transport through Micro Porous Layers
, M.Sc. Thesis Sharif University of Technology ; Shamloo, Amir (Supervisor) ; Noori, Ali (Supervisor)
Abstract
Fuel cell is a power generator like internal combustion engines, but the first point is that internal combustion engines produce mechanical power while fuel cells produce electrical power. Secondly, internal combustion engines use hydrocarbon derivatives such as gas as fuel and their exhaust fumes are toxic gaseous, but fuel cells use hydrogen as fuel and their exhaust are only water in either vapor or liquid form. One of the most important issues in fuel cells is optimum design of micro channels of bipolar plates which is different regarding the type and application of fuel cells. Optimum designing of micro channels on bipolar plates plays a key role in fluid mass transport through micro...
Flow Control in Vacuum Assisted Resin Transfer Molding
, M.Sc. Thesis Sharif University of Technology ; Shojaei, Akbar (Supervisor) ; Pishvaie, Mahmoud Reza (Supervisor)
Abstract
Vacuum assisted resin transfer molding (VARTM) is one of the most efficient and low cost process in composite industries. In this process, the preform is covered by a flexible vacuum bag and resin flows into the mold with applying vacuum pressure at the vent. The main objective in VARTM process is preventing voids and dry spots formation in final composite part because these defects may significantly deteriorate the mechanical properties of a structure. Flow front is an important parameter in this process which have a high influence on the void formation. Resin flow control is required to prevent dry spots or micro voids during the VARTM process. In general, the flow control is classified...
Hydrodynamic Simulation and Flow Pattern Analysis of Shark Undulation Motions
, Ph.D. Dissertation Sharif University of Technology ; Abbaspour Tehrani Fard, Majid (Supervisor)
Abstract
Many species in nature exist which human can reach the aims of flying and swimming by inspiring from them. Observations show that fish can use their especial undulating motions of body/fins to crusing, increase performance, suddenly acceleration, and maneuvering. To design a robot fish and benefit the characteristics and abilities of a live fish, using its real geometry and kinematics in the robot is vital. Therefore, simulations are essential to better exploiting the fish behavior, which can obtain useful consequences by using computational fluid dynamics. In this thesis, first the kinematics of sharks is investigated. Then, investigations are accomplished by utilizing an unsteady finite...
Numerical Analysis of Flow Pattern around Pile Groups (Two Piles)
, M.Sc. Thesis Sharif University of Technology ; Ataie Ashtiani, Behzad (Supervisor) ; Beheshti, Ali Asghar (Co-Advisor)
Abstract
Numerical simulations and large eddy simulations (LES) of turbulent flow around single pile, circular tandem piles, circular and square side-by-side piles at different spacing ratios (centre to centre distance to the pile diameter) with flow Reynolds number of 105 on the fixed flat-bed are presented. The calculations are performed using a computational fluid dynamics model, FLOW-3D, which solves the Navier-Stokes equations in three dimensions with finite volume method. Numerical simulations are validated by comparing the numerical results of time-averaged flow patterns around single and side-by-side piles with that of the experimental measurements. At the downstream of single pile,...
Investigation of bed Stability in Downstream for the Diversion dam under Scour (Mill & Moghan case study)
, M.Sc. Thesis Sharif University of Technology ; Shamsai, Abolfazl (Supervisor)
Abstract
Numerical simulations and large eddy simulations (LES) of turbulent flow downstream of diversion dam , pool-riffle bedform in different geometrical ratios (different lengths of riffle and pool) with flow Reynolds number of 3.0 E+04 to 3.3E+04, downstream of special case study "Mill and Moghan diversion dam" with Froude number of 0.5 are presented The calculations are performed using a computational fluid dynamics model, FLOW-3D, which solves the Navier-Stokes equations in three dimensions with finite volume method. Numerical simulations are validated by comparing the numerical results of time-averaged flow patterns downstream of pool-riffle sequence with that of the experimental...
Experimental Investigation of Flow Pattern around Pile Groups (two piles)
, M.Sc. Thesis Sharif University of Technology ; Ataie-Ashtiani, Behzad (Supervisor)
Abstract
The occurrence and development of scour hole around bridge pier are the main causes of bridge destruction. To predict manner, occurrence, development and final situation of scour hole around pier is the most important in the hydraulic design of bridges. A large number of studies have been performed to estimate the scour depth around piers at simplified laboratory conditions. The available equations from these studies do partly not present acceptable solutions. This issue is especially of great importance to the pile groups. For accurate determination of scour depth, it is required to get a better understanding of the flow and governing mechanism around pier. Although the flow pattern...
Experimental Study on Two-Phase Flow Characteristics in Micro-Channels
, M.Sc. Thesis Sharif University of Technology ; Nouri, Ali (Supervisor)
Abstract
The present study provids an experimental investigation on two-pase flow characteristics in microchannels. Experiment were conducted with a mixture of air and water in horizontal circular pyrex channel with 400µm inner diameter. The pressure drop and flow rates of the liquid and gas were measured using new method and images of the flow patterns recorded by high shutter speed camera. The gas and liquid superficial velocity ranges were 0.025-12.5m/s and 0.016-3.6m/s, respectively. The flow pattern map is developed from the observed flow patterns based on phases superficial velocity as wel as We numbers of liquid and gas phases. The flow pattern map is compared with those of larger channels....
High frequency oscillatory flow in micro channels
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Vol. 460 , 2014 , pp. 355-360 ; ISSN: 09277757 ; Javadi, A ; Bastani, D ; Miller, R ; Sharif University of Technology
Abstract
This paper deals with computational and experimental studies on the oscillatory flow at high frequencies up to 100. Hz performed with the Oscillating Drop and Bubble Analyzer (ODBA) setup based on the capillary pressure technique. The CFD results are validated considering pressure amplitude experimental data. The simulated results of phase shift between the generated oscillatory flow and the consequent pressure amplitudes show also good agreement with the experimental data. In absence of any compressibility and viscoelasticity effects and assumptions, a complex velocity field during oscillation is the main reason for the observation of a phase shift. The results of velocity profiles at the...