Download or read book Quasi Steady Capillary Corner Flow written by John Alex Baker and published by . This book was released on 2010 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is possible to drain slender containers filled with wetting liquids via capillary flows along the interior corners of the container. Usually the well established equations governing such flows demand numerical techniques. In the case of container draining unique boundary conditions resulting from local section geometry allow for a quasi-steady assumption and in turn permit analytical solutions. The quasi-steady assumption may also be employed for certain problems in which the corner flows cause passive capillary migration of the fluid within the container. The analytic solutions are useful because of the ease in which geometric effects may be observed. Container draining and capillary migration by means of corner flows are studied in a variety of container geometries. It is shown that careful selection of cross sectional shape can be used to maximize drain rates and minimize capillary migration times. Three-dimensional effects for these flows are investigated in tapering containers. Some simple micro-scale experiments are reported that provide confidence in the assumptions and application of the important boundary conditions that enable the solutions.

Download or read book An Analysis of Capillary Flow in Finite Length Interior Corners written by and published by . This book was released on 2021 with total page 107 pages. Available in PDF, EPUB and Kindle. Book excerpt: We analyze the mathematical robustness of slow massively parallel interior corner flows in low gravity environments. An interior corner provides a preferential orientation in low gravity environments. This is a luxury usually only found on earth. It also provides a passive pumping mechanism due to geometry of a conduit. The driving force for this flow is a pressure difference due to local surface curvature gradients. An alternative reasoning is that due to the geometrical constraints the interior corner surface energy is unbounded below. This results in the liquid wicking into corners indefinitely. Interior corner flow's main quantity of interest is the meniscus height h(z,t). With this variable one can calculate an average velocity w̄, flow rate Q, and volume of liquid in the corner V. Our study is different from most as it is highly in-depth look at finite domains, while the majority of previous solutions focus on similarity solutions of infinite, or semi-infinite domains. Boundary conditions, more specifically the functions that are assigned to the governing equation, play an integral role to meniscus height. We study a simplified problem of corners initially filled with quiescent liquid at t = 0, and boundary conditions are instantaneously applied when t > 0. Approximate asymptotic expressions are found for this process, but more importantly a method of approximating nonlinear heat equations as a sequence of linear heat equations is proved as a viable method for engineering purposes. Time varying boundary conditions are analyzed using a method of model-approximation. This is where we simply remove the nonlinearity of the governing equation and insert a fitting term n. The method works surprising well for a range of constant and time varying boundary conditions. In all cases the relative error between solutions is less than 10%. This is a major theme of the thesis, that is, force initial value boundary value problems to be linear via a substitution and achieve results sufficient for engineering analysis. For parallel corners, volume can transfer between corners in a multiple corner system. This motivates formulating an ODE governing the average height H(t) instead of meniscus height h(z,t). We formulate an N corner start-up problem similar to the analysis of a single corner. This solution is only true for a quasi-steady process for creeping flows. In order to feed a corner fluid, manifold tubing is required. Tubing presents a drastic geometrical difference where manifold resistance is much greater then the corner. This means for parallel flows that the dynamics of the system is governed by the transients introduced by the corner's ability to store volume. Real world system fluid properties can vary from temperature, concentration, and other gradients. These effects alter the meniscus height. We consider temperature and concentration gradients which add additional terms to the spatial derivative side of the equation. The property variation is captured by only three axial location-dependent coefficient functions. Finally, corners that are pinned along the top edge are shown to have a governing equation with a similar form to meniscus height h(z,t) equation. The simplifications used to establish analytical results can also be utilized for numerical solutions, difference being that the new quantity of interest is now the axially-dependent contact angle function [theta](z,t), which is now free to pivot about the top edge of the groove.

Download or read book Capillary Flow and Collapse in Wedge Shaped Channels written by Jörg Klatte and published by Cuvillier Verlag. This book was released on 2012-01-16 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: The forced, isothermal, and incompressible capillary channel flow has been studied theoretically, experimentally, and numerically in this work using the example of an open wedge-shaped channel with a finite length. The curvature of the interface at the open side of the channel is coupled to the pressure difference between the surrounding gas pressure and liquid pressure along the flow path, and thus, a flow rate limit exists, above which the interface collapses. This work investigates this collapse phenomenon as a function of the channel geometry. The derivation of a one-dimensional differential flow equation is based on the streamline theory. The local pressure loss and both principal mean radii of curvature at the free surface are considered. To approximate the local pressure loss, the fully-developed flow profiles were compared to the three-dimensional numerical flow profiles. The physical understanding of the collapse behavior is generalized with the detection of a second characteristic collapse phenomena. In the inertial limit, the interface chokes at the smallest cross-section. In the viscous limit, the interface collapses at the outlet. A dimensionless number has been introduced, which classifies the inertial and viscous regime. Three numerical methods are presented to solve the capillary flow problems. The first method is a fast numerical tool for design and parametric studies of steady capillary flows. The second numerical approach solves the complete three-dimensional equation system for validation of the theoretical assumptions and time-dependent flows. The third method is specialist and solves the governing one-dimensional equations within seconds. Unique experimental data for inertia dominated flow has been recorded using the microgravity environment of a drop tower. The steady flow configuration, the transient reorientation behavior of the interface, and the collapse behavior have been observed. Additional terrestrial experiments study the hydrostatic influence. The experimental results validate the theoretical work and benchmark the numerical codes. The evaluation of a three-dimensional numerical parametric study reveals the desired velocity scale for the critical flow rate in the inertial and viscous regime. The study improves the physical understanding of such capillary corner flows, which is beneficial for liquid management in space as well as for the development of microfluidic applications on the ground.

Download or read book Capillary Flow in an Interior Corner written by Mark Milton Weislogel and published by . This book was released on 1996 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capillary Flow in an Interior Corner written by Mark M. Weislogel and published by . This book was released on 1996 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capillary Driven Flows Along Differentially Wetted Interior Corners written by Eric L. Golliher and published by BiblioGov. This book was released on 2013-07 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Closed-form analytic solutions useful for the design of capillary flows in a variety of containers possessing interior corners were recently collected and reviewed. Low-g drop tower and aircraft experiments performed at NASA to date show excellent agreement between theory and experiment for perfectly wetting fluids. The analytical expressions are general in terms of contact angle, but do not account for variations in contact angle between the various surfaces within the system. Such conditions may be desirable for capillary containment or to compute the behavior of capillary corner flows in containers consisting of different materials with widely varying wetting characteristics. A simple coordinate rotation is employed to recast the governing system of equations for flows in containers with interior corners with differing contact angles on the faces of the corner. The result is that a large number of capillary driven corner flows may be predicted with only slightly modified geometric functions dependent on corner angle and the two (or more) contact angles of the system. A numerical solution is employed to verify the new problem formulation. The benchmarked computations support the use of the existing theoretical approach to geometries with variable wettability. Simple experiments to confirm the theoretical findings are recommended. Favorable agreement between such experiments and the present theory may argue well for the extension of the analytic results to predict fluid performance in future large length scale capillary fluid systems for spacecraft as well as for small scale capillary systems on Earth.

Download or read book Capillary driven Corner Flow in Weakly 3 dimensional Conduits and Contact Line Interface Dynamics in Reduced Gravity Environments written by Ryan Marcos Jenson and published by . This book was released on 2008 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Steady Capillary Driven Flow written by and published by . This book was released on 1996 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Computation of Capillary Flow in Interior Corners written by Cory L. Nardin and published by . This book was released on 2005 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Capillary Flows in Heterogeneous and Random Porous Media written by Rachid Ababou and published by John Wiley & Sons. This book was released on 2019-02-06 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt: Capillary phenomena occur in both natural and human-made systems, from equilibria in the presence of solids (grains, walls, metal wires) to multiphase flows in heterogeneous and fractured porous media. This book, composed of two volumes, develops fluid mechanics approaches for two immiscible fluids (water/air or water/oil) in the presence of solids (tubes, joints, grains, porous media). Their hydrodynamics are typically dominated by capillarity and viscous dissipation. This first volume presents the basic concepts and investigates two-phase equilibria, before analyzing two-phase hydrodynamics in discrete and/or statistical systems (tubular pores, planar joints). It then studies flows in heterogeneous and stratified porous media, such as soils and rocks, based on Darcy’s law. This analysis includes unsaturated flow (Richards equation) and two-phase flow (Muskat equations). Overall, the two volumes contain basic physical concepts, theoretical analyses, field investigations and statistical and numerical approaches to capillary-driven equilibria and flows in heterogeneous systems

Download or read book Capillary Flow in Interconnected Interior Corners and Other Exciting Adventures written by Ben Semerjian and published by . This book was released on 2009 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Open Channel Microfluidics written by Jean Berthier and published by Morgan & Claypool Publishers. This book was released on 2019-09-04 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Open microfluidics, the study of microflows having a boundary with surrounding air, encompasses different aspects such as paper or thread-based microfluidics, droplet microfluidics and open-channel microfluidics. Open-channel microflow is a flow at the micro-scale, guided by solid structures, and having at least a free boundary (with air or vapor) other than the advancing meniscus. This book is devoted to the study of open-channel microfluidics which (contrary to paper or thread or droplet microfluidics) is still very sparsely documented, but bears many new applications in biology, biotechnology, medicine, material and space sciences. Capillarity being the principal force triggering an open microflow, the principles of capillarity are first recalled. The onset of open-channel microflow is next analyzed and the fundamental notion of generalized Cassie angle (the apparent contact angle which accounts for the presence of air) is presented. The theory of the dynamics of open-channel microflows is then developed, using the notion of averaged friction length which accounts for the presence of air along the boundaries of the flow domain. Different channel morphologies are studied and geometrical features such as valves and capillary pumps are examined. An introduction to two-phase open-channel microflows is also presented showing that immiscible plugs can be transported by an open-channel flow. Finally, a selection of interesting applications in the domains of space, materials, medicine and biology is presented, showing the potentialities of open-channel microfluidics.

Download or read book Capillary Flow at Extreme Pressures written by Robert McDowell Williams and published by . This book was released on 1939 with total page 101 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lubricant transport towards tribocontact in capillary surface structures written by Klima, Joachim and published by KIT Scientific Publishing. This book was released on 2018-11-13 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: To counter lubricant shortage at a frictional contact (starvation), lubrication liquids, e.g. oils, are actively transported from a distant location towards the undersupplied tribocontact. This is done via small channels or generally via structures cut into a flat surface. In this way one can use capillary force as a cheap and reliable driver of the lubricant flow. Numerical modeling and experiments show that this method can be considered a promising new option to enhance tribocontact operation.

Download or read book Capillary Surfaces written by Dieter W. Langbein and published by Springer. This book was released on 2003-07-01 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: Featuring a foreword by the astronaut Ulf Merbold, this book is devoted to interfaces between two fluids, that is, between a liquid and a gas or between two liquids. It is the first review on the subject, providing an up-to-date overview.

Download or read book CRC Handbook of Thermal Engineering written by Raj P. Chhabra and published by CRC Press. This book was released on 2017-11-08 with total page 1801 pages. Available in PDF, EPUB and Kindle. Book excerpt: The CRC Handbook of Thermal Engineering, Second Edition, is a fully updated version of this respected reference work, with chapters written by leading experts. Its first part covers basic concepts, equations and principles of thermodynamics, heat transfer, and fluid dynamics. Following that is detailed coverage of major application areas, such as bioengineering, energy-efficient building systems, traditional and renewable energy sources, food processing, and aerospace heat transfer topics. The latest numerical and computational tools, microscale and nanoscale engineering, and new complex-structured materials are also presented. Designed for easy reference, this new edition is a must-have volume for engineers and researchers around the globe.

Download or read book Analytical Computational and Experimental Studies of Capillary Flow in Complex Geometries written by Yongqing Pent and published by . This book was released on 2009 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamic processes of capillary flow in complex geometries have been studied analytically, computationally and experimentally in this research. A general approach for modeling the capillary flow in arbitrary irregular geometries with straight axis of symmetry is proposed. Using this approach, the governing equation to describe the dynamic capillary rising motion in capillaries with nonuniform elliptical cross-section is first derived under the assumptions of parabolic distribution of the axial velocity and constant angle. The calculation results for the capillary flow in different tubes with irregular wall show that, in comparison with existing models that have been tested, the present model can improve the underestimation of the nonuniformity effects. Using the perturbation method, an asymptotic solution of the flow field in nonuniform circular tubes is obtained and is shown to be superior to the traditional Hagen-Poisuille solutions in comparison to the numerical FLUENT results. A new DCA (dynamic contact angle) model, combining the current velocity-dependent model based on molecular-kinetic theory and empirical time-dependent model based experiments, is proposed to describe the dynamic transition process from the initial state to the equilibrium state. The capillary flow model is further developed by using the new velocity distribution and the DCA model. The proposed theoretical models are validated by a series of experiments of capillary flow in complex geometries. The industrial application of the research was explored by adopting the proposed model to describe the water flow through a multi-layer porous medium that is used in Procter & Gamble's dewatering device for the paper making industry. Comparing with the experimental data, the proposed model has good predictions on the dewatering performance of the device, and hence, can potentially be used as an industrial design optimization tool.