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  • Open Access

    ARTICLE

    NUMERICAL INVESTIGATIONS ON COMBUSTION AND EMISSION CHARACTERISTICS IN A DIRECT INJECTION DIESEL ENGINE AT ELEVATED FUEL TEMPERATURES

    Manimaran Renganathan, Thundil Karuppa Raj Rajagopal*

    Frontiers in Heat and Mass Transfer, Vol.4, No.1, pp. 1-11, 2013, DOI:10.5098/hmt.v4.1.3008

    Abstract In this work, fuel spray parameters are studied by varying the fuel temperature. To overcome the tedious experimental task, a 3-D Computational Fluid Dynamics methodology is adopted by injecting fuel at specified temperatures of 313 K, 353 K and 393 K. The validation is accomplished after the optimal spatial and temporal steps of discretization are found out. At a fuel temperature of 313 K, advancing the injection timing from 6 deg bTDC to 20 deg bTDC increases cylinder peak pressure from 79.8 bar to 90.9 bar. Relation between the emission characteristics and spray SMD and temperature is studied. More >

  • Open Access

    ARTICLE

    ANALYSIS OF CHAOTIC NATURAL CONVECTION IN A TALL RECTANGULAR CAVITY WITH NON-ISOTHERMAL WALLS

    Heather Dillona , Ashley Emeryb,† , Ann Mescherb

    Frontiers in Heat and Mass Transfer, Vol.4, No.2, pp. 1-9, 2013, DOI:10.5098/hmt.v4.2.3004

    Abstract A computational model is presented that extends prior work on unsteady natural convection in a tall rectangular cavity with aspect ratio 10 and applies Proper Orthogonal Decomposition to the results. The solution to the weakly compressible Navier-Stokes equation is computed for a range of Rayleigh numbers between 2 × 107 and 2.2 × 108 with Prandtl number 0.71. A detailed spectral analysis shows dynamic system behavior beyond the Hopf bifurcation that was not previously observed. The wider Rayleigh range reveals new dynamic system behavior for the rectangular geometry, specifically a return to a stable oscillatory behavior that was not predicted… More >

  • Open Access

    ARTICLE

    COMPUTATIONAL STUDIES OF SWIRL RATIO AND INJECTION TIMING ON ATOMIZATION IN A DIRECT INJECTION DIESEL ENGINE

    Renganathan Manimarana, Rajagopal Thundil Karuppa Rajb,*

    Frontiers in Heat and Mass Transfer, Vol.5, pp. 1-9, 2014, DOI:10.5098/hmt.5.2

    Abstract Diesel engine combustion modeling presents a challenging task with the formation and breakup of spray into droplets. In this work, 3D-CFD computations are performed to understand the behaviour of spray droplet diameter and temperature during the combustion by varying the swirl ratio and injection timing. After the validation and grid and time independency tests, it is found that increase in swirl ratio from 1.4 to 4.1 results in peak pressure rise of 8 bar and an advancement of injection timing from 6 deg bTDC to 20 deg bTDC results in increase of peak pressure by 15 %. More >

  • Open Access

    ARTICLE

    Chemically Radiative MHD Flow of a Micropolar Nanofluid over a Stretching/Shrinking Sheet with a Heat Source or Sink

    Parakapali Roja1, Shaik Mohammed Ibrahim2, Thummala Sankar Reddy3, Giulio Lorenzini4,*

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 257-274, 2024, DOI:10.32604/fdmp.2023.042283

    Abstract This study examines the behavior of a micropolar nanofluid flowing over a sheet in the presence of a transverse magnetic field and thermal effects. In addition, chemical (first-order homogeneous) reactions are taken into account. A similarity transformation is used to reduce the system of governing coupled non-linear partial differential equations (PDEs), which account for the transport of mass, momentum, angular momentum, energy and species, to a set of non-linear ordinary differential equations (ODEs). The Runge-Kutta method along with shooting method is used to solve them. The impact of several parameters is evaluated. It is shown that the micro-rotational velocity of… More >

  • Open Access

    REVIEW

    Flow Regimes in Bubble Columns with and without Internals: A Review

    Ayat N. Mahmood1, Amer A. Abdulrahman1, Laith S. Sabri1,*, Abbas J. Sultan1, Hasan Shakir Majdi2, Muthanna H. Al-Dahhan3

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.2, pp. 239-256, 2024, DOI:10.32604/fdmp.2023.028015

    Abstract Hydrodynamics characterization in terms of flow regime behavior is a crucial task to enhance the design of bubble column reactors and scaling up related methodologies. This review presents recent studies on the typical flow regimes established in bubble columns. Some effort is also provided to introduce relevant definitions pertaining to this field, namely, that of “void fraction” and related (local, chordal, cross-sectional and volumetric) variants. Experimental studies involving different parameters that affect design and operating conditions are also discussed in detail. In the second part of the review, the attention is shifted to cases with internals of various types (perforated… More >

  • Open Access

    ARTICLE

    Dynamics along the epithelial-cancer biointerface: Hidden system complexities

    IVANA PAJIC-LIJAKOVIC*, MILAN MILIVOJEVIC

    BIOCELL, Vol.47, No.11, pp. 2321-2334, 2023, DOI:10.32604/biocell.2023.043796

    Abstract The biointerface dynamics influence any cancer spreading through the epithelium since it is documented in the early stages some malignancies (like epithelial cancer). The altered rearrangement of epithelial cells has an impact on the development of cancer. Therefore, it is necessary to comprehend the underlying biological and physical mechanisms of this biointerface dynamics for early suppression of cancer. While the biological mechanisms include cell signaling and gene expression, the physical mechanisms are several physical parameters such as the epithelial-cancer interfacial tension, epithelial surface tension, and compressive stress accumulated within the epithelium. Although the segregation of epithelia-cancer co-cultured systems was widely… More > Graphic Abstract

    Dynamics along the epithelial-cancer biointerface: Hidden system complexities

  • Open Access

    ARTICLE

    EFFECT OF DIFFERENT SHAPES ON CHARACTERISTICS OF CONJUGATE HEAT TRANSFER OF MICRO CHANNEL HEAT SINK

    Ankit Kanor, R Manimaran*

    Frontiers in Heat and Mass Transfer, Vol.7, pp. 1-5, 2016, DOI:10.5098/hmt.7.25

    Abstract One of the effective liquid cooling techniques for microelectronic devices is attaching micro channel heat sink to the inactive side of chip. A micro channel heat sink is a device that decreases temperature by flowing coolant through micro channels. The present study focuses on the conjugate heat transfer analyses for different cross-sections (trapezoidal, hexagonal, octagonal and circular).After present study is validated with the published result in the literature, the comparative study of parallel and counter flow configuration is performed. Different geometries are modeled using CATIA V5 software and simulated in ANSYS Fluent R14. From these CFD simulations, preferred configuration of… More >

  • Open Access

    ARTICLE

    An Analysis of the Dynamic Behavior of Damaged Reinforced Concrete Bridges under Moving Vehicle Loads by Using the Moving Mesh Technique

    Fabrizio Greco*, Paolo Lonetti, Arturo Pascuzzo, Giulia Sansone

    Structural Durability & Health Monitoring, Vol.17, No.6, pp. 457-483, 2023, DOI:10.32604/sdhm.2023.030075

    Abstract This work proposes a numerical investigation on the effects of damage on the structural response of Reinforced Concrete (RC) bridge structures commonly adopted in highway and railway networks. An effective three-dimensional FE-based numerical model is developed to analyze the bridge’s structural response under several damage scenarios, including the effects of moving vehicle loads. In particular, the longitudinal and transversal beams are modeled through solid finite elements, while horizontal slabs are made of shell elements. Damage phenomena are also incorporated in the numerical model according to a smeared approach consistent with Continuum Damage Mechanics (CDM). In such a context, the proposed… More >

  • Open Access

    ARTICLE

    Flow Breakdown of Hybrid Nanofluid on a Rigid Surface with Power Law Fluid as Lubricated Layers

    Mirza Naveed Jahangeer Baig1, Nadeem Salamat1, Sohail Nadeem2,3,*, Naeem Ullah2, Mohamed Bechir Ben Hamida4,5,6, Hassan Ali Ghazwani7, Sayed M. Eldin8, A. S. Al-Shafay9

    CMES-Computer Modeling in Engineering & Sciences, Vol.138, No.2, pp. 1485-1499, 2024, DOI:10.32604/cmes.2023.029351

    Abstract This work investigates an oblique stagnation point flow of hybrid nanofluid over a rigid surface with power law fluid as lubricated layers. Copper (Cu) and Silver (Ag) solid particles are used as hybrid particles acting in water H2O as a base fluid. The mathematical formulation of flow configuration is presented in terms of differential system that is nonlinear in nature. The thermal aspects of the flow field are also investigated by assuming the surface is a heated surface with a constant temperature T. Numerical solutions to the governing mathematical model are calculated by the RK45 algorithm. The results based on… More >

  • Open Access

    ARTICLE

    The Effect of Lateral Offset Distance on the Aerodynamics and Fuel Economy of Vehicle Queues

    Lili Lei*, Ze Li, Haichao Zhou, Jing Wang, Wei Lin

    FDMP-Fluid Dynamics & Materials Processing, Vol.20, No.1, pp. 147-163, 2024, DOI:10.32604/fdmp.2023.030158

    Abstract The vehicle industry is always in search of breakthrough energy-saving and emission-reduction technologies. In recent years, vehicle intelligence has progressed considerably, and researchers are currently trying to take advantage of these developments. Here we consider the case of many vehicles forming a queue, i.e., vehicles traveling at a predetermined speed and distance apart. While the majority of existing studies on this subject have focused on the influence of the longitudinal vehicle spacing, vehicle speed, and the number of vehicles on aerodynamic drag and fuel economy, this study considers the lateral offset distance of the vehicle queue. The group fuel consumption… More >

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