Fluid-Wall Interactions in Pseudopotential Lattice Boltzmann Models

Designing proper fluid-wall interaction forces to achieve proper wetting conditions is an important area of interest in pseudopotential lattice Boltzmann models. In this paper, we propose a modified fluid-wall interaction force that applies for pseudopotential models of both single-component fluids and partially miscible multicomponent fluids, such as hydrocarbon mixtures. A reliable correlation that predicts the resulting liquid contact angle on a flat solid surface is also proposed. This correlation works well over a wide variety of pseudopotential lattice Boltzmann models and thermodynamic conditions

Lessons from Two Years of ePortfolio Implementation in Engineering Technology Courses

In an undergraduate as well as in a graduate academic setting, an ePortfolio is a collection of student work designed to exhibit student’s achievements, which often includes student’s reflective commentaries. While in academia ePortfolios are used to document the student learning process over time, they have been also well received by employers as work portfolios or showcases. This paper provides detailed explanations of two years of implementation of ePortfolio activities in junior and senior level engineering technology courses. The goal of the paper is to present to the community the best practices learned during the implementation and to provide information on how the ePortfolios can be integrated with other course assignments, enhancing the course outcomes but without raising the burden from the instructor perspective. Class material samples are provided in the Appendix. The best received implementation was observed when: 1) scaffolding of the activity was done along the semester and was aligned with the pre-existing course activities (such as test, HW assignments, etc.), 2) the eP project was made optional for extra credit, 3) detailed instructions were provided, and 4) a website template was provided

Fugacity-Based Lattice Boltzmann Method for Multicomponent Multiphase Systems

The free-energy model can extend the lattice Boltzmann method to multiphase systems. However, there is a lack of models capable of simulating multicomponent multiphase fluids with partial miscibility. In addition, existing models cannot be generalized to honor thermodynamic information provided by any multicomponent equation of state of choice. In this paper, we introduce a free-energy lattice Boltzmann model where the forcing term is determined by the fugacity of the species, the thermodynamic property that connects species partial pressure to chemical potential calculations. By doing so, we are able to carry out multicomponent multiphase simulations of partially miscible fluids and generalize the methodology for use with any multicomponent equation of state of interest. We test this fugacity-based lattice Boltzmann method for the cases of vapor-liquid equilibrium for two- and three-component mixtures in various temperature and pressure conditions. We demonstrate that the model is able to reliably reproduce phase densities and compositions as predicted by multicomponent thermodynamics and can reproduce different characteristic pressure-composition and temperature-composition envelopes with a high degree of accuracy. We also demonstrate that the model can offer accurate predictions under dynamic conditions

Attainment of Rigorous Thermodynamic Consistency and Surface Tension in Single-Component Pseudopotential Lattice Boltzmann Models via a Customized Equation of State

The lack of thermodynamic consistency is a well-recognized problem in the single-component pseudopotential lattice Boltzmann models which prevents them from replicating accurate liquid and vapor phase densities; i.e., current models remain unable to exactly match coexisting density values predicted by the associated thermodynamic model. Most of the previous efforts had attempted to solve this problem by introducing tuning parameters, whose determination required empirical trial and error until acceptable thermodynamic consistency was achieved. In this study, we show that the problem can be alternatively solved by properly designing customized equations of state (EOSs) that replace any cubic EOS of choice during the computation of effective mass used in Shan-Chen forces. A two-parameter cubic-shaped customized EOS is introduced. Contrary to previous efforts, customization parameters in the new EOS are nonempirical and are rather derived from solving the integral mechanical stability equation, which neglects the need for any type of tuning for the attainment of rigorous thermodynamic consistency. The proposed approach reduces the errors of the coexisting densities and saturated pressure in the simulation to a maximum of 0.01% within the liquid-vapor density ratio range from O1 to O(104), which had not been achieved in any of the previous tuning-based efforts. A straightforward way for achieving the desired surface tension via the customized EOS is also provided

Tecnología e innovación para reinventar a Colombia

Las tendencias tecnológicas traen consigo un inmenso potencial transformador. La proliferación de teléfonos y sensores inteligentes ya triplican en cantidad a los siete mil millones de humanos que habitamos la tierra y eso genera torrentes masivos de datos que, tan solo en los últimos cinco años, sobrepasan la información creada en toda nuestra historia. Esto supone también el advenimiento del increíble poder de las redes sociales, que han habilitado un debate y conversación global en tiempo real, brindando voz y voto a miles de millones de personas en todas las esferas de la sociedad, derrocando gobiernos, transformando leyes y hasta las constituciones de los países

Manual Revision Process for Project-Based Laboratory Instruction

A four-step laboratory manual revision process was developed in this study based upon a technical writing process for supporting project-based laboratory classes. The audience and the objectives of this type of laboratory manuals are quite different from those of traditional, descriptive laboratory classes. The project-based laboratory manual has to serve as both an operational handbook and a theoretical textbook. The proposed four-step manual revision process was implemented in the fall 2016 semester in a 3-credit, senior elective class which was built upon a commercially-rated finite element analysis software package. Student surveys and evaluations showed that the revision process greatly increased student engagement in the class and, as a result, increased student learning effectiveness

Para construir el futuro de Colombia

Al nivel más básico interpreto el lema, que hace las veces de título para este artículo, como un llamado a la acción dirigido a todos los colombianos que hemos tenido la fortuna de acceder a la educación, hasta obtener un grado profesional. Quiero que lo veamos como un ejercicio que se debe articular de manera precisa: nuestra ambición de lo que esperamos alcanzar para el país, en los próximos quince o veinte años

Implementing Peer-Review Activities for Engineering Writing Assignments

Professional engineers spend a considerable portion of their day writing, yet disciplinary writing skills are not addressed in many engineering courses. This study investigates peer review as a mean to enhance student writing in engineering courses. Students completed formative peer reviews using an online peer review system for a group project in a fluid mechanics course (with online and face-to-face sections) and for an individual writing assignment in a senior capstone class in mechanical engineering. A university-wide rubric for disciplinary writing was used to assess student writing performance on interim and final assignments completed over the course of a semester. Online surveys were used to assess student perceptions of the peer review process. The study was implemented over two semesters with iterative revisions in instruction made between semesters based on initial findings. Results suggest that peer review can increase student performance, as long as reflections are used to prompt student revision, regardless of the class delivery method or assignment type