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- All Subjects: Mechanical Engineering
- All Subjects: engineering
- Creators: Herrmann, Marcus
- Resource Type: Text
Description
Contact angle goniometer is one of the most common tools in surfaces science. Since the introduction of this instrument by Fox and Zisman1 in 1950, dispensing the liquid using a syringe has generated pendant drops. However, using such approach at conditions significantly deviating from standard pressure and temperature would require an elaborate and costly fluidic system. To this end, this thesis work introduces alternative design of a goniometer capable of contact angle measurement at wide pressure and temperature range. In this design, pendant droplets are not dispensed through a pipette but are generated through localized condensation on a tip of a preferentially cooled small metal wire encapsulated within a thick thermal insulator layer. This thesis work covers experimental study of the relation between the geometry of the condensation-based pendant drop generator geometry and subcooling, and growth rate of drops of representative high (water) and low (pentane) surface tension liquids. Several routes that the generated pendant drops can be used to measure static and dynamic contact angles of the two liquids on common substrates well as nanoengineered superhydrophobic and omniphobic surfaces are demonstrated.
ContributorsMohan, Ajay Roopesh (Author) / Rykaczewski, Konrad (Thesis advisor) / Herrmann, Marcus (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2015
Description
The Volume-of-Fluid method is a popular method for interface tracking in Multiphase applications within Computational Fluid Dynamics. To date there exists several algorithms for reconstruction of a geometric interface surface. Of these are the Finite Difference algorithm, Least Squares Volume-of-Fluid Interface Reconstruction Algorithm, LVIRA, and the Efficient Least Squares Volume-of-Fluid Interface Reconstruction Algorithm, ELVIRA. Along with these geometric interface reconstruction algorithms, there exist several volume-of-fluid transportation algorithms. This paper will discuss two operator-splitting advection algorithms and an unsplit advection algorithm. Using these three interface reconstruction algorithms, and three advection algorithms, a comparison will be drawn to see how different combinations of these algorithms perform with respect to accuracy as well as computational expense.
ContributorsKedelty, Dominic (Author) / Herrmann, Marcus (Thesis advisor) / Huang, Huei-Ping (Committee member) / Chen, Kangping (Committee member) / Arizona State University (Publisher)
Created2015
Description
Multi-pulse particle tracking velocimetry (multi-pulse PTV) is a recently proposed flow measurement technique aiming to improve the performance of conventional PTV/ PIV. In this work, multi-pulse PTV is assessed based on PTV simulations in terms of spatial resolution, velocity measurement accuracy and the capability of acceleration measurement. The errors of locating particles, velocity measurement and acceleration measurement are analytically calculated and compared among quadruple-pulse, triple-pulse and dual-pulse PTV. The optimizations of triple-pulse and quadruple-pulse PTV are discussed, and criteria are developed to minimize the combined error in position, velocity and acceleration. Experimentally, the velocity and acceleration fields of a round impinging air jet are measured to test the triple-pulse technique. A high speed beam-splitting camera and a custom 8-pulsed laser system are utilized to achieve good timing flexibility and temporal resolution. A new method to correct the registration error between CCDs is also presented. Consequently, the velocity field shows good consistency between triple-pulse and dual-pulse measurements. The mean acceleration profile along the centerline of the jet is used as the ground truth for the verification of the triple-pulse PIV measurements of the acceleration fields. The instantaneous acceleration field of the jet is directly measured by triple-pulse PIV and presented. Accelerations up to 1,000 g's are measured in these experiments.
ContributorsDing, Liuyang (Author) / Adrian, Ronald J. (Thesis advisor) / Herrmann, Marcus (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2014
Description
Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because of their strong adhesion to a majority of substrates. This unusual high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In the first part of the thesis, we described a multiscale study aiming at understanding the fundamental mechanisms governing wetting and adhesion of gallium-based liquid metals. In particular, macroscale dynamic contact angle measurements were coupled with Scanning Electron Microscope (SEM) imaging to relate macroscopic drop adhesion to morphology of the liquid metal-surface interface. In addition, room temperature liquid-metal microfluidic devices are also attractive systems for hyperelastic strain sensing. Currently two types of liquid metal-based strain sensors exist for inplane measurements: single-microchannel resistive and two-microchannel capacitive devices. However, with a winding serpentine channel geometry, these sensors typically have a footprint of about a square centimeter, limiting the number of sensors that can be embedded into. In the second part of the thesis, firstly, simulations and an experimental setup consisting of two GaInSn filled tubes submerged within a dielectric liquid bath are used to quantify the effects of the cylindrical electrode geometry including diameter, spacing, and meniscus shape as well as dielectric constant of the insulating liquid and the presence of tubing on the overall system's capacitance. Furthermore, a procedure for fabricating the two-liquid capacitor within a single straight polydiemethylsiloxane channel is developed. Lastly, capacitance and response of this compact device to strain and operational issues arising from complex hydrodynamics near liquid-liquid and liquid-elastomer interfaces are described.
ContributorsLiu, Shanliangzi (Author) / Rykaczewski, Konrad (Thesis advisor) / Alford, Terry (Committee member) / Herrmann, Marcus (Committee member) / Hildreth, Owen (Committee member) / Arizona State University (Publisher)
Created2015
Description
Conventional fluid dynamics models such as the Navier-Stokes equations are derived for prediction of fluid motion at or near equilibrium, classic examples being the motion of fluids for which inter-molecular collisions are dominant. Flows at equilibrium permit simplifications such as the introduction of viscosity and also lead to solutions that are single-valued. However, many other regimes of interest include "fluids"' far from equilibrium; for example, rarefied gases or particle-laden flows in which the dispersed phase can be comprised of granular solids, droplets, or bubbles. Particle motion in these flows is not typically dominated by collisions and may exhibit significant memory effects; therefore, is often poorly described using continuum, field-based (Eulerian) approaches. Non-equilibrium flows generally lack a straightforward counterpart to viscosity and their multi-valued solutions cannot be represented by most Eulerian methods. This strongly motivates different strategies to address current shortcomings and the novel approach adopted in this work is based on the Conditional Quadrature Method of Moments (CQMOM). In CQMOM, moment equations are derived from the Boltzmann equation using a quadrature approximation of the velocity probability density function (PDF). CQMOM circumvents the drawbacks of current methods and leads to multivariate and multidimensional solutions in an Eulerian frame of reference. In the present work, the discretized PDF is resolved using an adaptive two-point quadrature in three-dimensional velocity space. The method is applied to computation of a series of non-equilibrium flows, ranging from simple two-dimensional test cases to fully-turbulent three-dimensional wall-bounded particle-laden flows. The primary contribution of the present effort is on development, application, and assessment of CQMOM for predicting the key features of dilute particle-laden flows. Statistical descriptors such as mean concentration and mean velocity are in good agreement with previous results, for both collision-less and collisional flows at varying particle Stokes numbers. Turbulent statistics and measures of local accumulation agree less favorably with prior results and identify areas for improvement in the modeling strategy.
ContributorsDunn, Dennis Martin (Author) / Squires, Kyle D. (Thesis advisor) / Calhoun, Ronald J. (Committee member) / Chen, Kangping (Committee member) / Dai, Lenore L. (Committee member) / Herrmann, Marcus (Committee member) / Arizona State University (Publisher)
Created2015
A level set approach for denoising and adaptively smoothing complex geometry stereolithography files
Description
Stereolithography files (STL) are widely used in diverse fields as a means of describing complex geometries through surface triangulations. The resulting stereolithography output is a result of either experimental measurements, or computer-aided design. Often times stereolithography outputs from experimental means are prone to noise, surface irregularities and holes in an otherwise closed surface.
A general method for denoising and adaptively smoothing these dirty stereolithography files is proposed. Unlike existing means, this approach aims to smoothen the dirty surface representation by utilizing the well established levelset method. The level of smoothing and denoising can be set depending on a per-requirement basis by means of input parameters. Once the surface representation is smoothened as desired, it can be extracted as a standard levelset scalar isosurface.
The approach presented in this thesis is also coupled to a fully unstructured Cartesian mesh generation library with built-in localized adaptive mesh refinement (AMR) capabilities, thereby ensuring lower computational cost while also providing sufficient resolution. Future work will focus on implementing tetrahedral cuts to the base hexahedral mesh structure in order to extract a fully unstructured hexahedra-dominant mesh describing the STL geometry, which can be used for fluid flow simulations.
A general method for denoising and adaptively smoothing these dirty stereolithography files is proposed. Unlike existing means, this approach aims to smoothen the dirty surface representation by utilizing the well established levelset method. The level of smoothing and denoising can be set depending on a per-requirement basis by means of input parameters. Once the surface representation is smoothened as desired, it can be extracted as a standard levelset scalar isosurface.
The approach presented in this thesis is also coupled to a fully unstructured Cartesian mesh generation library with built-in localized adaptive mesh refinement (AMR) capabilities, thereby ensuring lower computational cost while also providing sufficient resolution. Future work will focus on implementing tetrahedral cuts to the base hexahedral mesh structure in order to extract a fully unstructured hexahedra-dominant mesh describing the STL geometry, which can be used for fluid flow simulations.
ContributorsKannan, Karthik (Author) / Herrmann, Marcus (Thesis advisor) / Peet, Yulia (Committee member) / Frakes, David (Committee member) / Arizona State University (Publisher)
Created2014
Description
Hydraulic fracturing is an effective technique used in well stimulation to increase petroleum well production. A combination of multi-stage hydraulic fracturing and horizontal drilling has led to the recent boom in shale gas production which has changed the energy landscape of North America.
During the fracking process, highly pressurized mixture of water and proppants (sand and chemicals) is injected into to a crack, which fractures the surrounding rock structure and proppants help in keeping the fracture open. Over a longer period, however, these fractures tend to close due to the difference between the compressive stress exerted by the reservoir on the fracture and the fluid pressure inside the fracture. During production, fluid pressure inside the fracture is reduced further which can accelerate the closure of a fracture.
In this thesis, we study the stress distribution around a hydraulic fracture caused by fluid production. It is shown that fluid flow can induce a very high hoop stress near the fracture tip. As the pressure gradient increases stress concentration increases. If a fracture is very thin, the flow induced stress along the fracture decreases, but the stress concentration at the fracture tip increases and become unbounded for an infinitely thin fracture.
The result from the present study can be used for studying the fracture closure problem, and ultimately this in turn can lead to the development of better proppants so that prolific well production can be sustained for a long period of time.
During the fracking process, highly pressurized mixture of water and proppants (sand and chemicals) is injected into to a crack, which fractures the surrounding rock structure and proppants help in keeping the fracture open. Over a longer period, however, these fractures tend to close due to the difference between the compressive stress exerted by the reservoir on the fracture and the fluid pressure inside the fracture. During production, fluid pressure inside the fracture is reduced further which can accelerate the closure of a fracture.
In this thesis, we study the stress distribution around a hydraulic fracture caused by fluid production. It is shown that fluid flow can induce a very high hoop stress near the fracture tip. As the pressure gradient increases stress concentration increases. If a fracture is very thin, the flow induced stress along the fracture decreases, but the stress concentration at the fracture tip increases and become unbounded for an infinitely thin fracture.
The result from the present study can be used for studying the fracture closure problem, and ultimately this in turn can lead to the development of better proppants so that prolific well production can be sustained for a long period of time.
ContributorsPandit, Harshad Rajendra (Author) / Chen, Kang P (Thesis advisor) / Herrmann, Marcus (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2014
Description
Many defense, healthcare, and energy applications can benefit from the development of surfaces that easily shed droplets of liquids of interest. Desired wetting properties are typically achieved via altering the surface chemistry or topography or both through surface engineering. Despite many recent advancements, materials modified only on their exterior are still prone to physical degradation and lack durability. In contrast to surface engineering, this thesis focuses on altering the bulk composition and the interior of a material to tune how an exterior surface would interact with liquids. Fundamental and applied aspects of engineering of two material systems with low contact angle hysteresis (i.e. ability to easily shed droplets) are explained. First, water-shedding metal matrix hydrophobic nanoparticle composites with high thermal conductivity for steam condensation rate enhancement are discussed. Despite having static contact angle <90° (not hydrophobic), sustained dropwise steam condensation can be achieved at the exterior surface of the composite due to low contact angle hysteresis (CAH). In order to explain this observation, the effect of varying the length scale of surface wetting heterogeneity over three orders of magnitude on the value of CAH was experimentally investigated. This study revealed that the CAH value is primarily governed by the pinning length which in turn depends on the length scale of wetting heterogeneity. Modifying the heterogeneity size ultimately leads to near isotropic wettability for surfaces with highly anisotropic nanoscale chemical heterogeneities. Next, development of lubricant-swollen polymeric omniphobic protective gear for defense and healthcare applications is described. Specifically, it is shown that the robust and durable protective gear can be made from polymeric material fully saturated with lubricant that can shed all liquids irrespective of their surface tensions even after multiple contact incidences with the foreign objects. Further, a couple of schemes are proposed to improve the rate of lubrication and replenishment of lubricant as well as reduce the total amount of lubricant required in making the polymeric protective gear omniphobic. Overall, this research aims to understand the underlying physics of dynamic surface-liquid interaction and provides simple scalable route to fabricate better materials for condensers and omniphobic protective gear.
ContributorsDamle, Viraj (Author) / Rykaczewski, Konrad (Thesis advisor) / Phelan, Patrick (Committee member) / Lin, Jerry (Committee member) / Herrmann, Marcus (Committee member) / Wang, Robert (Committee member) / Wang, Liping (Committee member) / Arizona State University (Publisher)
Created2017
Description
Durable, cost-effective, and environmentally friendly anti-icing methods are desired to reduce the icing hazard in many different industrial areas including transportation systems, power plants, power transmission, as well as offshore oil and gas production. In contrast to traditional passive anti-icing surfaces, this thesis work introduces an anti-icing coating that responds to different icing conditions by releasing an antifreeze liquid. It consists of an outer porous superhydrophobic epidermis and a wick-like underlying dermis that is infused with the antifreeze liquid. This bi-layer coating prevents accumulation of frost, freezing fog, and freezing rain, while conventional anti-icing surfaces typically work only in one of these conditions. The bi-layer coating also delays condensation on the exterior surface at least ten times longer than identical system without antifreeze.
It is demonstrated that the significant delay in condensation onset is due to the integral humidity sink effect posed by the hygroscopic antifreeze liquid infused in the porous structure. This effect significantly alters the water vapor concentration field at the coating surface, which delays nucleation of drops and ice. It was demonstrated that with a proper design of the environmental chamber the size of the region of inhibited condensation and condensation frosting around an isolated pore, as well as periodically spaced pores, filled by propylene glycol can be quantitatively predicted from quasi-steady state water vapor concentration field. Theoretical analysis and experiments revealed that the inhibition of nucleation is governed by only two non-dimensional geometrical parameters: the pore size relative to the unit cell size and the ratio of the unit cell size to the thickness of the boundary layer. It is demonstrated that by switching the size of the pores from millimeters to nanometers, a dramatic depression of the nucleation onset temperature, as well as significantly greater delay in nucleation onset can be achieved.
It is demonstrated that the significant delay in condensation onset is due to the integral humidity sink effect posed by the hygroscopic antifreeze liquid infused in the porous structure. This effect significantly alters the water vapor concentration field at the coating surface, which delays nucleation of drops and ice. It was demonstrated that with a proper design of the environmental chamber the size of the region of inhibited condensation and condensation frosting around an isolated pore, as well as periodically spaced pores, filled by propylene glycol can be quantitatively predicted from quasi-steady state water vapor concentration field. Theoretical analysis and experiments revealed that the inhibition of nucleation is governed by only two non-dimensional geometrical parameters: the pore size relative to the unit cell size and the ratio of the unit cell size to the thickness of the boundary layer. It is demonstrated that by switching the size of the pores from millimeters to nanometers, a dramatic depression of the nucleation onset temperature, as well as significantly greater delay in nucleation onset can be achieved.
ContributorsSun, Xiaoda (Author) / Rykaczewski, Konrad (Thesis advisor) / Lin, Jerry (Committee member) / Phelan, Patrick (Committee member) / Wang, Robert (Committee member) / Herrmann, Marcus (Committee member) / Wang, Liping (Committee member) / Arizona State University (Publisher)
Created2017
Numerical Modeling of Cake Formation and Permeate Flux Decline in Membrane Filtration Using OpenFOAM
Description
Membrane filtration is an important technology in industry. In the past few decades, equations have been developed from experimental results to predict cake formation and permeate flux decline in the membrane filtration process. In the current work, the block of particles on membrane surface is achieved by setting surface flux on membrane surface zero. This approach is implemented for both microfiltration and nanofiltration using OpenFOAM. Moreover, a new method to deal with cake resistance for nanofiltration is introduced. Cake resistance is applied to both cake and membrane. To validate the new techniques, results of crossflow microfiltration are compared to theoretical results and results of two crossflow nanofiltration cases are compared to experimental data. In addition, the new techniques are applied to dead end filtration to observe the different structure of the cake and explore the effect of resistance on velocity profile.
ContributorsHu, Jueming (Author) / Herrmann, Marcus (Thesis advisor) / Huang, Huei-Ping (Committee member) / Lee, Taewoo (Committee member) / Arizona State University (Publisher)
Created2018