| 1. |
- Mark, Andreas, 1980, et al.
(författare)
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Simulation of a Non-Newtonian Dense Granular Suspension in a Microfluidic Contraction
- 2013
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Ingår i: 8th International Conference on Multiphase Flow.
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Konferensbidrag (refereegranskat)abstract
- The success of a solder paste jet printer is based on an uninterrupted flow of fluid, specifically dense fluid suspensions, through a series of ducts inside the printing head. It is well known that the flow of dense suspensions is prone to jamming and sedimentation effects, both of which could entail detrimental failure modes in the printing heads. A thorough understanding of the fluid dynamics of suspensions as they flow through ducts and connections is of utmost importance. The purpose of this study is to propose a novel simulation framework and to show that it captures the main effects such as mass flow and partial jamming in a cylindrical duct test configuration. The granular suspension is a generic solder paste with solder particlesimmersed in a flux. The simulations are performed in the multi-phase flow solver IBOFlow. A two fluid model is used for the granular suspension and the discretization is done an Euler-Euler framework. The averaged momentum equations from Enwald et al. (1996) are solved together with the common continuity equation generating a shared pressure field. Explicit constitutive equations for the interfacial momentum transfer and particle pressure are employed. To capture the shear thinning effects of the non-Newtonian suspensions the standard Carreau rheology model is used. To study how the fluid flow affects the local volume fraction and partial jamming in the duct, simulations are performed for different applied pressure drops ranging from one to five bars. For both particle pressure models, the resulting mean bulk velocities are compared with experiments with good agreement, and partial jamming is observed. Hence, it is concluded that the proposed framework is suitable to model and simulate the granular suspension in a micro fluid contraction.
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| 2. |
- Hu, Zhili, 1983, et al.
(författare)
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Detecting single molecules inside a carbon nanotube to control molecular sequences using inertia trapping phenomenon
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 101:13, s. Art. no. 133105-
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Tidskriftsartikel (refereegranskat)abstract
- Here we show the detection of single gas molecules inside a carbon nanotube based on the change inresonance frequency and amplitude associated with the inertia trapping phenomenon. As its directimplication, a method for controlling the sequence of small molecule is then proposed to realize theconcept of manoeuvring of matter atom by atom in one dimension. The detection as well as theimplication is demonstrated numerically with the molecular dynamics method. It is theoreticallyassessed that it is possible for a physical model to be fabricated in the very near future.
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| 3. |
- Hu, Z. L., et al.
(författare)
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Molecular dynamics simulation of inertial trapping-induced atomic scale mass transport inside single walled carbon nanotubes
- 2013
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 102:8
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Tidskriftsartikel (refereegranskat)abstract
- The forced transverse vibration of a single-walled carbon nanotube (SWNT) embedded with atomic-size particles was investigated using molecular dynamic simulations. The particles inside the cylindrical cantilever can be trapped near the antinodes or at the vicinity of the SWNT tip. The trapping phenomenon is highly sensitive to the external driving frequencies such that even very small changes in driving frequency can have a strong influence on the probability of the location of the particle inside the SWNT. The trapping effect could potentially be employed to realize the atomic scale control of particle position inside an SWNT via the finite adjustment of the external driving frequency. It may also be suggested that the trapping phenomenon could be utilized to develop high-sensitive mass detectors based on a SWNT resonator.
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| 4. |
- Mårtensson, Gustaf, 1972
(författare)
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Jet Printing of low temperature solder paste
- 2013
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Ingår i: IPC APEX EXPO Conference and Exhibition 2013, APEX EXPO 2013. - 9781627485456 ; 1, s. 296-313
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Konferensbidrag (refereegranskat)abstract
- Low temperature paste offers a production solution for advanced applications • Jet printing furthers these opportunities.
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| 5. |
- Ramachandraiah, Harisha, et al.
(författare)
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Dean flow-coupled inertial focusing in curved channels
- 2014
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Ingår i: Biomicrofluidics. - : AIP Publishing. - 1932-1058. ; 8:3, s. 034117-
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Tidskriftsartikel (refereegranskat)abstract
- Passive particle focusing based on inertial microfluidics was recently introduced as a high-throughput alternative to active focusing methods that require an external force field to manipulate particles. In inertial microfluidics, dominant inertial forces cause particles to move across streamlines and occupy equilibrium positions along the faces of walls in flows through straight micro channels. In this study, we systematically analyzed the addition of secondary Dean forces by introducing curvature and show how randomly distributed particles entering a simple u-shaped curved channel are focused to a fixed lateral position exiting the curvature. We found the lateral particle focusing position to be fixed and largely independent of radius of curvature and whether particles entering the curvature are pre-focused (at equilibrium) or randomly distributed. Unlike focusing in straight channels, where focusing typically is limited to channel cross-sections in the range of particle size to create single focusing point, we report here particle focusing in a large cross-section area (channel aspect ratio 1: 10). Furthermore, we describe a simple u-shaped curved channel, with single inlet and four outlets, for filtration applications. We demonstrate continuous focusing and filtration of 10 mu m particles (with > 90% filtration efficiency) from a suspension mixture at throughputs several orders of magnitude higher than flow through straight channels (volume flow rate of 4.25ml/min). Finally, as an example of high throughput cell processing application, white blood cells were continuously processed with a filtration efficiency of 78% with maintained high viability. We expect the study will aid in the fundamental understanding of flow through curved channels and open the door for the development of a whole set of bio-analytical applications.
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