Jaime Klapp

GRAVITATIONAL COLLAPSE AND FRAGMENTATION OF MOLECULAR CLOUD CORES

The detected multiplicity of main-sequence and pre-main-sequence stars along with the emerging evidence for binary and multiple protostars, imply that stars may ultimately form by fragmentation of collapsing molecular cloud cores. These discoveries, coupled with recent observational knowledge of the structure of dense cloud cores and of the properties of young binary stars, provide serious constraints to the theory of star formation. Most theoretical progress in the field of star formation is largely based on numerical calculations of the early collapse and fragmentation of protostellar clouds. Although these models have been quite successful at predicting the formation of binary protostars, a direct comparison between theory and observations has not yet been established. The results of recent observations as well as of early and recent analytic and numerical models, on which the present theory of star formation is based, are reviewed here in a self-consistent manner.

Computational and Experimental Fluid Mechanics with Applications to Physics, Engineering and the Environment

We study the scaling of adsorption isotherms of polyacrylic dispersants on generic surfaces of metallic oxides XnOm as a function of the number of monomeric units, using Electrostatic Dissipative Particle Dynamics simulations. The simulations show how the scaling properties in these systems emerge and how the isotherms rescale to a universal curve, reproducing reported experimental results. The critical exponent for these systems is also obtained, in perfect agreement with the scaling theory of deGennes. Some important applications are mentioned.Virtually all economic sectors as well as many public and private activities are affected in some measure by changes in weather and climate. Uncertainties in the scope and severity of these changes pose financial and social risks for individuals, businesses, and government agencies, with direct influence on food security and production, transport, health, electricity generation, and water resources. The vulnerability of human settlement to extreme weather and climate episodes is a further aspect that must be emphasized. Hence, achieving accurate weather and climate forecasts has important implications to modern society. In this chapter, we present an overview of the basic fluid-mechanical principles that govern the behaviour of weather and climate. We shall mainly focus on the numerical modelling of weather prediction and climate projections, spanning the range from the very first attempts, based on simple barotropic models, to the development of general circulation models of the atmosphere and ocean to the most recent multi-model ensemble forecasting systems. L. Di G. Sigalotti (B) · E. Sira · L. Trujillo Centro de Física, Instituto Venezolano de Investigaciones Científicas, IVIC, Apartado Postal 20632, Caracas 1020-A, Venezuela e-mail: leonardo.sigalotti@gmail.com E. Sira e-mail: eloy.sira@gmail.com J. Klapp Departamento de Física, Instituto Nacional de Investigaciones Nucleares, ININ, Km. 36.5, Carretera México-Toluca, 52750 La Marquesa, Estado de México, Mexico e-mail: jaime.klapp@inin.gob.mx J. Klapp Departamento de Matemáticas, Cinvestav del Instituto Politécnico Nacional (I. P. N.), 07360 México, D. F., Mexico e-mail: jaime.klapp@hotmail.com L. Trujillo The Abdus Salam International Centre for Theoretical Physics, ICTP, Strada Costiera 11, 34014 Trieste, Italy e-mail: leonardo.trujillo@gmail.com L. Di G. Sigalotti et al. (eds.), Computational and Experimental Fluid Mechanics with 3 Applications to Physics, Engineering and the Environment, Environmental Science and Engineering, DOI:10.1007/978-3-319-00191-3_1,

Experimental and Computational Fluid Mechanics

In this work, the stability of a strongly non-parallel symmetrical counterflow mixed convection problem is studied, using numerically generated eigenfunctions. The base flow is numerically obtained for each value of the buoyancy parameter (Richardson number), and the stability of this flow is analyzed by increasing its value while all the others remained fixed. The perturbed linear functions are numerically generated by introducing a transient modulated asymmetrical buoyancy, relaxing at later times to ‘numerical eigenfunctions’. The time evolution of the amplitude of these perturbations is used to obtain the stability characteristics. Symmetry breaking instability occurs, for fixed geometry, Reynolds and Prandtl numbers, for values of the buoyancy parameter larger than a critical one. However, there is also a window for the buoyancy parameter below this critical value, where the system shows instability, producing a slightly asymmetric thermal and flow response.

Flooding hazard assessment at Tulancingo (Hidalgo, Mexico): Flooding hazard assessment at Tulancingo (Hidalgo, Mexico)

In recent decades, the Tulancingo municipality (Mexico), has been affected by numerous extreme weather phenomena that caused heavy flooding events with severe damage to property and people. Most of the weather phenomena placed several dams under hydrologic risk. The hurricane “ Dean”, in 2007, led to the overflow of the dam “ La Esperanza”, generating inundations that reached levels of 1 m in Tulancingo. Mexico does not have a specific regulation that establishes critical thresholds for the construction of flooding hazard maps. With the aim to provide a tool for the flooding hazard assessment, we performed a numerical study of inundation waterdepths by means of the IBER software. The study is based on the construction of different inundation scenarios that are based on the hydrologic study of “ La Esperanza” dams basin, associated to regional precipitation and different return periods. Inundation waterdepths, flow velocity and land use were used to construct flooding hazard maps. We calculated the occurrence probability of the considered inundation events. The hazard maps presented here and the evaluation of the flooding likelihood can support long-term planning that would help minimize the impact of such events in Tulancingo.

Energy for the Present and Future: A World Energy Overview

For many years coal and oil have been used as energy sources. Currently oil is the dominant source of energy, but experts predict that in a few decades it will no longer be profitable. Burning fossil fuels generates atmospheric contaminants that give rise to the greenhouse effect that artificially warms the earth, damages the earth ozone layer, and produces acid rain, all of which are very dangerous for living beings. As a consequence, abnormal phenomena such as the melting of glaciers, changes in the Gulf Stream, unprecedented heat waves, floods, hurricanes, and damage to marine organisms are now occurring. Although there are many skeptics, there is a general consensus that the earth is warming up. In order to reduce CO2 and other greenhouse gas emissions, the extensive use of alternative and cleaner sources of energy have been proposed, including CO2 emission-free nuclear energy and other alternative sources, among which are hydraulic, hydrogen, solar, eolic, biomass and geothermal. Another future alternative is to use methane hydrates, which have clean combustion and are believed to have considerable, still-unexplored reserves. It is also important to implement measures to improve energy efficiency for reducing greenhouse gas emissions. In this paper we review present and future energy sources, including both primary non-renewable and alternative sources of energy. There is still time to take corrective measures by replacing some polluting fuels with clean sources of energy that can contribute to inherit a clean and sustainable world for future generations.

A Template for Scalable Continuum Dynamic Simulations in Multiple GPUs

In this work we present a programming philosophy and a template code for achieving computational scalability when using multiple graphics processing units (GPUs) in the numerical solution of any mathematical system of equations found in continuum dynamic simulations. The programming philosophy exploits the principal characteristics of the GPU hardware, with emphasis in the delivering of threads with massive memory fetches, intense calculations using local registers and limited writes to global memory. The philosophy requires explicit formulas for calculations for which domain decomposition is trivial. The domains are decomposed in regions that use the local central processing unit (CPU) to communicate common interfaces using the message passing interface (MPI). A template code for the heat equation is established and tested for scalability. The novelty is that we show a series of codes, constructed from the basic template, that solve all the basic model equations found in continuum dynamics, and present illustrative results. The model equations are the heat equation, the Poisson equation, the shallow-water equations, the flow in porous media equations and the vorticity equations.

GPU Simulations of Fluid and Composition Dispersion in a Porous Media with Smoothed Particle Hydrodynamics

Fluid and composition dispersion in a porous media plays a relevant role in some industrial processes. The proper characterization of the porous media and the dynamics of the involved fluids are key parameters for the study of some industrial processes. This characterization is a challenge for the numerical methods community. The SPH open-source code named DualSPHysics is presented as a new tool for evaluating the fluid dynamics in porous media. The code was developed using CUDA, which can be used for solving the system of equations on GPU devices. In particular, we report the obtained performance for the DualSPHysics code and a comparison between the efficient implementations for CPU and GPU.

Numerical Simulations of a Dam Overflowing. Case Study: “La Esperanza” Dam in Hidalgo, Mexico. Implications for Risk Evaluation

Dam safety is an issue that affects directly or indirectly all society sectors. Up to now, Mexico does not have a proper federal or state legislation to evaluate dam safety, thus it is difficult to assign liability when total or partial dam failure occurs or to prevent failure by programming cost-effective dam supervision. Dam safety risk analysis by means of numerical simulations has the objective of evaluating the occurrence probability of a phenomenon, or group of phenomena, that affects dam safety. This work is focused on obtaining the overflow probability of the dam “La Esperanza” located in Hidalgo, Mexico. With this purpose, first, a statistical hydrologic analysis using daily maximum rains was conducted to obtain dam inflow as a function of rainfall duration and return periods. Second, different inflow scenarios were simulated to obtain their associated maximum hydraulic head values using the Smoothed Particle Hydrodynamics (SPH) numerical method. Finally, simulation results of maximum hydraulic head reached by water particles were used to calculate the overflow probability. We have obtained a high overflow probability for the “La Esperanza” dam warranting more studies, for this and other dams with similar conditions, given that the hazard potential to populated downstream areas is high.

Fluid Dynamics in Physics, Engineering and Environmental Applications

The objective of this chapter is to review the importance of fluid dynamics research and its impact on science and technology. Here we consider four particular areas of study, namely environmental fluid mechanics, turbulence, nanoand microfluids, and biofluid dynamics, with deeper emphasis on environmental flows. Each of these topics is illustrative of how improved scientific knowledge of fluid dynamics can have a major impact on important national needs and worldwide economies, as well as help developed nations to maintain their leadership in the production of novel technologies. J. Klapp (&) Instituto Nacional de Investigaciones Nucleares, ININ, Km. 36.5, Carretera México-Toluca, 52750 La Marquesa, Estado de México, Mexico e-mail: jaime.klapp@hotmail.com J. Klapp Departamento de Matemáticas, Cinvestav del I.P.N., 07360 México, D.F., Mexico L. D. G. Sigalotti L. Trujillo Centro de Física, Instituto Venezolano de Investigaciones Científicas, IVIC, Apartado Postal 20632, 1020 Caracas, Venezuela e-mail: leonardo.sigalotti@gmail.com L. Trujillo e-mail: leonardo.trujillo@gmail.com L. Trujillo The Abdus Salam, International Centre for Theoretical Physics, ICTP, Trieste, Italy C. Stern Facultad de Ciencias, Universidad Nacional Autónoma de México, Ciudad Universitaria, C. Exterior s/n, 04510 Coyoacán, D.F., Mexico e-mail: catalina@ciencias.unam.mx J. Klapp et al. (eds.), Fluid Dynamics in Physics, Engineering and Environmental Applications, Environmental Science and Engineering, DOI: 10.1007/978-3-642-27723-8_1, Springer-Verlag Berlin Heidelberg 2013 3In this work we study the tertiary structure of ionic surfactants when the pH in the system is modified using electrostatic dissipative particle dynamics simulations (DPD). The dependence with pH and kind of surfactant is presented. Our simulations reproduce the experimental behavior reported in the literature. The scaling for the radius of gyration with the size of the molecule as a function of pH is also obtained.

FITspec: A New Algorithm for the Automated Fit of Synthetic Stellar Spectra for OB Stars

In this paper we describe the FIT\textit{spec} code, a data mining tool for the automatic fitting of synthetic stellar spectra. The program uses a database of 27\,000 {\sc cmfgen} models of stellar atmospheres arranged in a six-dimensional (6D) space, where each dimension corresponds to one model parameter. From these models a library of 2\,835\,000 synthetic spectra were generated covering the ultraviolet, optical, and infrared region of the electromagnetic spectrum. Using FIT\textit{spec} we adjust the effective temperature and the surface gravity. From the 6D array we also get the luminosity, the metallicity, and three parameters for the stellar wind: the terminal velocity (