Multiscale computational homogenization: review and proposal of a new enhanced-first-order method

This is a copy of the author 's final draft version of an article published in the Archives of computational methods in engineering. The final publication is available at Springer via http://dx.doi.org/10.1007/s11831-016-9205-0The continuous increase of computational capacity has encouraged the extensive use of multiscale techniques to simulate the material behaviour on several fields of knowledge. In solid mechanics, the multiscale approaches which consider the macro-scale deformation gradient to obtain the homogenized material behaviour from the micro-scale are called first-order computational homogenization. Following this idea, the second-order FE2 methods incorporate high-order gradients to improve the simulation accuracy. However, to capture the full advantages of these high-order framework the classical boundary value problem (BVP) at the macro-scale must be upgraded to high-order level, which complicates their numerical solution. With the purpose of obtaining the best of both methods i.e. first-order and second-order, in this work an enhanced-first-order computational homogenization is presented. The proposed approach preserves a classical BVP at the macro-scale level but taking into account the high-order gradient of the macro-scale in the micro-scale solution. The developed numerical examples show how the proposed method obtains the expected stress distribution at the micro-scale for states of structural bending loads. Nevertheless, the macro-scale results achieved are the same than the ones obtained with a first-order framework because both approaches share the same macro-scale BVP.Peer ReviewedPostprint (author's final draft

Direct simulation of liquid-gas-solid flow with a free surface lattice Boltzmann method

Direct numerical simulation of liquid-gas-solid flows is uncommon due to the considerable computational cost. As the grid spacing is determined by the smallest involved length scale, large grid sizes become necessary -- in particular if the bubble-particle aspect ratio is on the order of 10 or larger. Hence, it arises the question of both feasibility and reasonability. In this paper, we present a fully parallel, scalable method for direct numerical simulation of bubble-particle interaction at a size ratio of 1-2 orders of magnitude that makes simulations feasible on currently available super-computing resources. With the presented approach, simulations of bubbles in suspension columns consisting of more than $100\,000$ fully resolved particles become possible. Furthermore, we demonstrate the significance of particle-resolved simulations by comparison to previous unresolved solutions. The results indicate that fully-resolved direct numerical simulation is indeed necessary to predict the flow structure of bubble-particle interaction problems correctly.Comment: submitted to International Journal of Computational Fluid Dynamic

Homogenization of plain weave composites with imperfect microstructure: Part II--Analysis of real-world materials

A two-layer statistically equivalent periodic unit cell is offered to predict a macroscopic response of plain weave multilayer carbon-carbon textile composites. Falling-short in describing the most typical geometrical imperfections of these material systems the original formulation presented in (Zeman and \v{S}ejnoha, International Journal of Solids and Structures, 41 (2004), pp. 6549--6571) is substantially modified, now allowing for nesting and mutual shift of individual layers of textile fabric in all three directions. Yet, the most valuable asset of the present formulation is seen in the possibility of reflecting the influence of negligible meso-scale porosity through a system of oblate spheroidal voids introduced in between the two layers of the unit cell. Numerical predictions of both the effective thermal conductivities and elastic stiffnesses and their comparison with available laboratory data and the results derived using the Mori-Tanaka averaging scheme support credibility of the present approach, about as much as the reliability of local mechanical properties found from nanoindentation tests performed directly on the analyzed composite samples.Comment: 28 pages, 14 figure

Design and Numerical Analysis of Flow Characteristics in a Scaled Volute and Vaned Nozzle of Radial Turbocharger Turbines

[EN] Over the past few decades, the aerodynamic improvements of turbocharger turbines contributed significantly to the overall efficiency augmentation and the advancements in downsizing of internal combustion engines. Due to the compact size of automotive turbochargers, the experimental measurement of the complex internal aerodynamics has been insufficiently studied. Hence, turbine designs mostly rely on the results of numerical simulations and the validation of zero-dimensional parameters as efficiency and reduced mass flow. To push the aerodynamic development even further, a precise validation of three-dimensional flow patterns predicted by applied computational fluid dynamics (CFD) methods is in need. This paper presents the design of an up-scaled volute-stator model, which allows optical experimental measurement techniques. In a preliminary step, numerical results indicate that the enlarged geometry will be representative of the flow patterns and characteristic non-dimensional numbers at defined flow sections of the real size turbine. Limitations due to rotor-stator interactions are highlighted. Measurement sections of interest for available measurement techniques are predefined.The authors disclose receipt of the following financial support for the research, authorship, and/or publication of this article: This work was partly sponsored by the program "Ayuda a Primeros Proyectos de Investigacion (PAID-06-18), Vicerrectorado de Investigacion, Innovacion y Transferencia de la Universitat Politecnica de Valencia (UPV), Spain". The support given to Ms. N.H.G. by Universitat Politecnica de Valencia through the "FPI-Subprograma 2" (No.FPI-2018-S2-1368) grant within the "Programa de Apoyo para la Investigacion y Desarrollo (PAID-01-18)" is gratefully acknowledgedTiseira, A.; Navarro, R.; Inhestern, LB.; Hervás-Gómez, N. (2020). Design and Numerical Analysis of Flow Characteristics in a Scaled Volute and Vaned Nozzle of Radial Turbocharger Turbines. Energies. 13(11):1-19. https://doi.org/10.3390/en13112930S1191311Praveena, V., & Martin, M. L. J. (2018). A review on various after treatment techniques to reduce NOx emissions in a CI engine. Journal of the Energy Institute, 91(5), 704-720. doi:10.1016/j.joei.2017.05.010Sindhu, R., Amba Prasad Rao, G., & Madhu Murthy, K. (2018). Effective reduction of NOx emissions from diesel engine using split injections. Alexandria Engineering Journal, 57(3), 1379-1392. doi:10.1016/j.aej.2017.06.009Gil, A., Tiseira, A. O., García-Cuevas, L. M., Usaquén, T. R., & Mijotte, G. (2018). Fast three-dimensional heat transfer model for computing internal temperatures in the bearing housing of automotive turbochargers. International Journal of Engine Research, 21(8), 1286-1297. doi:10.1177/1468087418804949Suhrmann, J. F., Peitsch, D., Gugau, M., & Heuer, T. (2012). On the Effect of Volute Tongue Design on Radial Turbine Performance. Volume 8: Turbomachinery, Parts A, B, and C. doi:10.1115/gt2012-69525Roumeas, M., & Cros, S. (2012). Aerodynamic Investigation of a Nozzle Clearance Effect on Radial Turbine Performance. Volume 8: Turbomachinery, Parts A, B, and C. doi:10.1115/gt2012-68835Liu, Y., Yang, C., Qi, M., Zhang, H., & Zhao, B. (2014). Shock, Leakage Flow and Wake Interactions in a Radial Turbine With Variable Guide Vanes. Volume 2D: Turbomachinery. doi:10.1115/gt2014-25888Cornolti, L., Onorati, A., Cerri, T., Montenegro, G., & Piscaglia, F. (2013). 1D simulation of a turbocharged Diesel engine with comparison of short and long EGR route solutions. Applied Energy, 111, 1-15. doi:10.1016/j.apenergy.2013.04.016Bohbot, J., Chryssakis, C., & Miche, M. (2006). Simulation of a 4-Cylinder Turbocharged Gasoline Direct Injection Engine Using a Direct Temporal Coupling Between a 1D Simulation Software and a 3D Combustion Code. SAE Technical Paper Series. doi:10.4271/2006-01-3263Inhestern, L. B. (s. f.). Measurement, Simulation, and 1D-Modeling of Turbocharger Radial Turbines at Design and Extreme Off-Design Conditions. doi:10.4995/thesis/10251/119989Tamaki, H., & Unno, M. (2008). Study on Flow Fields in Variable Area Nozzles for Radial Turbines. International Journal of Fluid Machinery and Systems, 1(1), 47-56. doi:10.5293/ijfms.2008.1.1.047Eroglu, H., & Tabakoff, W. (1991). LDV Measurements and Investigation of Flow Field Through Radial Turbine Guide Vanes. Journal of Fluids Engineering, 113(4), 660-667. doi:10.1115/1.2926531Karamanis, N., Martinez-Botas, R. F., & Su, C. C. (2000). Mixed Flow Turbines: Inlet and Exit Flow Under Steady and Pulsating Conditions. Volume 1: Aircraft Engine; Marine; Turbomachinery; Microturbines and Small Turbomachinery. doi:10.1115/2000-gt-0470Galindo, J., Tiseira Izaguirre, A. O., García-Cuevas, L. M., & Hervás Gómez, N. (2020). Experimental approach for the analysis of the flow behaviour in the stator of a real centripetal turbine. International Journal of Engine Research, 22(6), 2010-2020. doi:10.1177/1468087420916281Dufour, G., Carbonneau, X., Cazalbou, J.-B., & Chassaing, P. (2006). Practical Use of Similarity and Scaling Laws for Centrifugal Compressor Design. Volume 6: Turbomachinery, Parts A and B. doi:10.1115/gt2006-91227Tancrez, M., Galindo, J., Guardiola, C., Fajardo, P., & Varnier, O. (2011). Turbine adapted maps for turbocharger engine matching. Experimental Thermal and Fluid Science, 35(1), 146-153. doi:10.1016/j.expthermflusci.2010.07.018Menter, F. R. (1994). Two-equation eddy-viscosity turbulence models for engineering applications. AIAA Journal, 32(8), 1598-1605. doi:10.2514/3.12149Broatch, A., Galindo, J., Navarro, R., & García-Tíscar, J. (2014). Methodology for experimental validation of a CFD model for predicting noise generation in centrifugal compressors. International Journal of Heat and Fluid Flow, 50, 134-144. doi:10.1016/j.ijheatfluidflow.2014.06.006Smirnov, P. E., Hansen, T., & Menter, F. R. (2007). Numerical Simulation of Turbulent Flows in Centrifugal Compressor Stages With Different Radial Gaps. Volume 6: Turbo Expo 2007, Parts A and B. doi:10.1115/gt2007-27376Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2014). Analysis and Methodology to Characterize Heat Transfer Phenomena in Automotive Turbochargers. Journal of Engineering for Gas Turbines and Power, 137(2). doi:10.1115/1.4028261Serrano, J. R., Olmeda, P., Arnau, F. J., Dombrovsky, A., & Smith, L. (2015). Turbocharger heat transfer and mechanical losses influence in predicting engines performance by using one-dimensional simulation codes. Energy, 86, 204-218. doi:10.1016/j.energy.2015.03.130Serrano, J. R., Tiseira, A., García-Cuevas, L. M., Inhestern, L. B., & Tartoussi, H. (2017). Radial turbine performance measurement under extreme off-design conditions. Energy, 125, 72-84. doi:10.1016/j.energy.2017.02.118Serrano, J. R., Gil, A., Navarro, R., & Inhestern, L. B. (2017). Extremely Low Mass Flow at High Blade to Jet Speed Ratio in Variable Geometry Radial Turbines and its Influence on the Flow Pattern: A CFD Analysis. Volume 8: Microturbines, Turbochargers and Small Turbomachines; Steam Turbines. doi:10.1115/gt2017-63368Serrano, J. R., Navarro, R., García-Cuevas, L. M., & Inhestern, L. B. (2019). Contribution to tip leakage loss modeling in radial turbines based on 3D flow analysis and 1D characterization. International Journal of Heat and Fluid Flow, 78, 108423. doi:10.1016/j.ijheatfluidflow.2019.108423Choi, M., Baek, J. H., Chung, H. T., Oh, S. H., & Ko, H. Y. (2008). Effects of the low Reynolds number on the loss characteristics in an axial compressor. Proceedings of the Institution of Mechanical Engineers, Part A: Journal of Power and Energy, 222(2), 209-218. doi:10.1243/09576509jpe520Klausner, E., & Gampe, U. (2014). Evaluation and Enhancement of a One-Dimensional Performance Analysis Method for Centrifugal Compressors. Volume 2D: Turbomachinery. doi:10.1115/gt2014-25141Tiainen, J., Jaatinen-Värri, A., Grönman, A., Turunen-Saaresti, T., & Backman, J. (2018). Effect of FreeStream Velocity Definition on Boundary Layer Thickness and Losses in Centrifugal Compressors. Journal of Turbomachinery, 140(5). doi:10.1115/1.4038872Vinuesa, R., Hosseini, S. M., Hanifi, A., Henningson, D. S., & Schlatter, P. (2017). Pressure-Gradient Turbulent Boundary Layers Developing Around a Wing Section. Flow, Turbulence and Combustion, 99(3-4), 613-641. doi:10.1007/s10494-017-9840-

A hybrid stabilization technique for simulating water wave - Structure interaction by incompressible Smoothed Particle Hydrodynamics (ISPH) method

The Smoothed Particle Hydrodynamics (SPH) method is emerging as a potential tool for studying water wave related problems, especially for violent free surface flow and large deformation problems. The incompressible SPH (ISPH) computations have been found not to be able to maintain the stability in certain situations and there exist some spurious oscillations in the pressure time history, which is similar to the weakly compressible SPH (WCSPH). One main cause of this problem is related to the non-uniform and clustered distribution of the moving particles. In order to improve the model performance, the paper proposed an efficient hybrid numerical technique aiming to correct the ill particle distributions. The correction approach is realized through the combination of particle shifting and pressure gradient improvement. The advantages of the proposed hybrid technique in improving ISPH calculations are demonstrated through several applications that include solitary wave impact on a slope or overtopping a seawall, and regular wave slamming on the subface of open-piled structure

Microstructural analysis of skeletal muscle force generation during aging.

Human aging results in a progressive decline in the active force generation capability of skeletal muscle. While many factors related to the changes of morphological and structural properties in muscle fibers and the extracellular matrix (ECM) have been considered as possible reasons for causing age-related force reduction, it is still not fully understood why the decrease in force generation under eccentric contraction (lengthening) is much less than that under concentric contraction (shortening). Biomechanically, it was observed that connective tissues (endomysium) stiffen as ages, and the volume ratio of connective tissues exhibits an age-related increase. However, limited skeletal muscle models take into account the microstructural characteristics as well as the volume fraction of tissue material. This study aims to provide a numerical investigation in which the muscle fibers and the ECM are explicitly represented to allow quantitative assessment of the age-related force reduction mechanism. To this end, a fiber-level honeycomb-like microstructure is constructed and modeled by a pixel-based Reproducing Kernel Particle Method (RKPM), which allows modeling of smooth transition in biomaterial properties across material interfaces. The numerical investigation reveals that the increased stiffness of the passive materials of muscle tissue reduces the force generation capability under concentric contraction while maintains the force generation capability under eccentric contraction. The proposed RKPM microscopic model provides effective means for the cellular-scale numerical investigation of skeletal muscle physiology. NOVELTY STATEMENT: A cellular-scale honeycomb-like microstructural muscle model constructed from a histological cross-sectional image of muscle is employed to study the causal relations between age-associated microstructural changes and age-related force loss using Reproducing Kernel Particle Method (RKPM). The employed RKPM offers an effective means for modeling biological materials based on pixel points in the medical images and allow modeling of smooth transition in the material properties across interfaces. The proposed microstructure-informed muscle model enables quantitative evaluation on how cellular-scale compositions contribute to muscle functionality and explain differences in age-related force changes during concentric, isometric and eccentric contractions