Loading...
Search for:
microvalve
0.01 seconds
Numerical study of diodicity mechanism in different tesla-type microvalves
, Article Journal of Applied Research and Technology ; Volume 11, Issue 6 , 2013 , Pages 876-885 ; 16656423 (ISSN) ; Shahsavan, M ; Paykani, A ; Sharif University of Technology
2013
Abstract
Microvalve is one of the most important components in microfluidic systems and micropumps. In this paper, threedimensional incompressible flow through a Tesla-type microvalve is simulated using FLUENT computational fluid dynamic package. The flow is laminar and SIMPLE algorithm is used. The second-order upwind method is implemented for discretizing convective terms. The diodicity mechanism is investigated in detail for three different microvalves. Effect of several series Tesla-type microvalves on diodicity is also studied. The numerical analyses reveal that the mechanism of diodicity occurs at the T-junction and side channel. If inlet and outlet channels are eliminated, diodicity can be...
Numerical study on the performance of Tesla type microvalve in a valveless micropump in the range of low frequencies
, Article Journal of Micro-Bio Robotics ; Volume 8, Issue 3 , 2013 , pp 145-159 ; 21946418 (ISSN) ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
Abstract
In this study, the performance of Tesla-type microvalves, used in micropumps for low frequency driving force, is examined. Three-dimensional and unsteady numerical analysis of fluid flow inside a valveless reciprocating micropump in the range of low working frequencies is carried out. Reciprocating movement of flow actuator provides the actuation and pumping of the working fluid. Ferrofluidic valveless micropump is one practical sample of this kind of micropumps that operate in the range of low working frequencies. To model the reciprocating movement of flow actuator, two time varying functions that includes sinusoidal and step excitation are employed. Also, the performance of...
Design and Fabrication of a Ferrofluidic Miniature Pump
, Ph.D. Dissertation Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor) ; Moosavi, Ali (Supervisor)
Abstract
This thesis presents the prototype design and fabrication of magnetically actuated miniature pumps which utilize self-sealing capability of ferrofluid-covered permanent magnets in both pumping and valving mechanisms. The contactless external actuation feature of the design enables integration of the pump with other PMMA-based microfluidic systems with low cost and disposability. The body of the 1st fabricated prototype pump consists of three nozzle/diffuser elements and two pumping chambers connected to the ends of a flat-wall pumping cylinder. A cylindrical permanent magnet placed inside the pumping cylinder acts as a piston which reciprocates by using an external magnetic actuator driven...
Fabrication of Ferrofluidic Micropump
, M.Sc. Thesis Sharif University of Technology ; Shafii, Mohammad Behshad (Supervisor) ; Saidi, Mohammad Said (Supervisor) ; Saidi, Mohammad Hassan (Supervisor)
Abstract
In this project, two Ferrofluidic micropumps that do not need any mechanical moving parts are presented. These micropumps are including simple microchannels containing magnetic fluid plugs that are used as flow actuator and the on/off valve. Using external magnetic field actuation in this type of micropumps, the magnetic fluid would have continuous motion in a channel with micrometer dimensions that would provide the main fluid to be pumped. Although the plug of magnetic fluid has surface contact with operative fluid, but considering its specific features, it would not compine with the pumping fluid. These micropumps may be used to pump the fluids or gases. The outcomes of the investigation...
Modeling and Analysis of Cylindrical Swellable Elastomers
, M.Sc. Thesis Sharif University of Technology ; Arghavani Hadi, Jamal (Supervisor)
Abstract
When swellable elastomer are surrounded by suitable fluid, they absorb the fluid and swell. This capability is used to design different tools. For example, drug release devises, sensors and actuators, in microfluidic devises such as micro-valves and micro-mixers, and seal devises. Most of these devises are shaped cylindrically. Therefore, have a thorough knowledge about how cylindrical swellable elastomer behavior, give us a good vision about how to design such actuators. In this thesis we have used constitutive equation of such materials and have investigated behavior of cylindrical swellable elastomers analytically and numerically. Analytical investigation is focused of transient behavior...
Numerical investigation on the effect of the size and number of stages on the tesla microvalve efficiency
, Article Journal of Mechanics ; Volume 29, Issue 3 , 2012 , Pages 527-534 ; 17277191 (ISSN) ; Kolahdouz, E. M ; Shirani, E ; Shafii, M. B ; Sharif University of Technology
2012
Abstract
In the present study, the effect of the number of stages of Tesla Micro-Valve (TMV), as well as the dependency of Reynolds number, Re, on the valve performance has been analyzed. For this purpose, different layouts include one to four-stage with different sizes are investigated numerically. The main criterion for evaluation of valves performance is diodicity, Di. Unsteady and steady flow in valve have been simulated and compared. It is shown that although there are some difference but the trend is similar for both responses. Finally, 2-D and steady state computations of the fluid flow have been utilized that reveal a strong dependence of Di on Re and pressure drop, ΔP. The results showed...
Hydromagnetic micropump and flow controller. part a: experiments with nickel particles added to the water
, Article Experimental Thermal and Fluid Science ; Volume 33, Issue 6 , 2009 , Pages 1021-1028 ; 08941777 (ISSN) ; Shafii, M. B ; Alavi Dehkordi, E ; Sharif University of Technology
2009
Abstract
The novel idea of the Hydromagnetic Micropump and Flow Controller (HMFC) is used in this paper to construct a laboratory setup capable of bidirectional pumping and controlling the flow in microtubes. A laboratory setup, which contains no moving parts, is integrated with a pressure-driven flow setup to make the presented HMFC device. The device operation is based on controllable motion of magnetic particles, added to the carrier fluid, caused by the magnetic field, produced by solenoids located just next to the microtube. The magnitude of these forces is proportional to the strength and gradient of magnetic field which, in turn, is related to the electrical current and arrangement of the...