Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry: Spray Simulations

The Terascale High-Fidelity Simulations of Turbulent Combustion (TSTC) project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of the approach is direct numerical simulation (DNS) featuring the highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. Under this component of the TSTC program the simulation code named S3D, developed and shared with coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for turbulent liquid fuel spray dynamics. Major accomplishments include improved fundamental understanding of mixing and auto-ignition in multi-phase turbulent reactant mixtures and turbulent fuel injection spray jets

Final report: Prototyping a combustion corridor

The Combustion Corridor is a concept in which researchers in combustion and thermal sciences have unimpeded access to large volumes of remote computational results. This will enable remote, collaborative analysis and visualization of state-of-the-art combustion science results. The Engine Research Center (ERC) at the University of Wisconsin - Madison partnered with Lawrence Berkeley National Laboratory, Argonne National Laboratory, Sandia National Laboratory, and several other universities to build and test the first stages of a combustion corridor. The ERC served two important functions in this partnership. First, we work extensively with combustion simulations so we were able to provide real world research data sets for testing the Corridor concepts. Second, the ERC was part of an extension of the high bandwidth based DOE National Laboratory connections to universities

Blood Vessels Under the Microscope

This paper looks at blood vessels. All humans and animals have blood vessels, including your pet rabbit or dog, a whale or a giraffe! We need blood vessels to stay alive. This paper answers many questions, including what blood vessels are used for and why we need them. It looks at how and why blood vessels grow and what they look like. It also explores what happens when things go wrong with blood vessels and if blood vessels are ever bad for us. So, if you want to know how many miles of blood vessels there are in your body, learn about problems astronauts have in space, see real blood vessels through a microscope, or learn how to keep your blood vessels healthy, you are reading the right article

Direct numerical simulation of turbulent counterflow nonpremixed flames

This paper presents our recent progress in terascale three-dimensional simulations of turbulent nonpremixed flames in the presence of a mean flow strain and fine water droplets. Under the ongoing university collaborative project supported by the DOE SciDAC Program [1] along with the INCITE 2007 Project [2], the study aims at bringing the state-of-the-art high-fidelity simulation capability to the next level by incorporating various advanced physical models for soot formation, radiative heat transfer, and lagrangian spray dynamics, to an unprecedented degree of detail in high-fidelity simulation application. The targeted science issue is fundamental characteristics of flame suppression by the complex interaction between turbulence, chemistry, radiation, and water spray. The high quality simulation data with full consideration of multi-physics processes will allow fundamental understanding of the key physical and chemical mechanisms in the flame quenching behavior. In this paper, recent efforts on numerical algorithms and model development toward the targeted terascale 3D simulations are discussed and some preliminary results are presented.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/58180/2/jpconf7_78_012029.pd

Terascale High-Fidelity Simulations of Turbulent Combustion with Detailed Chemistry

The TSTC project is a multi-university collaborative effort to develop a high-fidelity turbulent reacting flow simulation capability utilizing terascale, massively parallel computer technology. The main paradigm of our approach is direct numerical simulation (DNS) featuring highest temporal and spatial accuracy, allowing quantitative observations of the fine-scale physics found in turbulent reacting flows as well as providing a useful tool for development of sub-models needed in device-level simulations. The code named S3D, developed and shared with Chen and coworkers at Sandia National Laboratories, has been enhanced with new numerical algorithms and physical models to provide predictive capabilities for spray dynamics, combustion, and pollutant formation processes in turbulent combustion. Major accomplishments include improved characteristic boundary conditions, fundamental studies of auto-ignition in turbulent stratified reactant mixtures, flame-wall interaction, and turbulent flame extinction by water spray. The overarching scientific issue in our recent investigations is to characterize criticality phenomena (ignition/extinction) in turbulent combustion, thereby developing unified criteria to identify ignition and extinction conditions. The computational development under TSTC has enabled the recent large-scale 3D turbulent combustion simulations conducted at Sandia National Laboratories

Tropomyosin 1: multiple roles in the developing heart and in the formation of congenital heart defects

Tropomyosin 1 (TPM1) is an essential sarcomeric component, stabilising the thin filament and facilitating actin's interaction with myosin. A number of sarcomeric proteins, such as alpha myosin heavy chain, play crucial roles in cardiac development. Mutations in these genes have been linked to congenital heart defects (CHDs), occurring in approximately 1 in 145 live births. To date, TPM1 has not been associated with isolated CHDs. Analysis of 380 CHD cases revealed three novel mutations in the TPM1 gene; IVS1 + 2T > C, I130V, S229F and a polyadenylation signal site variant GATAAA/AATAAA. Analysis of IVS1 + 2T > C revealed aberrant pre-mRNA splicing. In addition, abnormal structural properties were found in hearts transfected with TPM1 carrying I130V and S229F mutations. Phenotypic analysis of TPM1 morpholino-treated embryos revealed roles for TPM1 in cardiac looping, atrial septation and ventricular trabeculae formation and increased apoptosis was seen within the heart. In addition, sarcomere assembly was affected and altered action potentials were exhibited. This study demonstrated that sarcomeric TPM1 plays vital roles in cardiogenesis and is a suitable candidate gene for screening individuals with isolated CHDs

Application of the Large-Eddy Approach to the Simulation of Turbulence in Uniform Shear Flow

In the Rogallo approach to the simulation of homogeneous turbulence in uniform shear flow, the equations of motion are solved in a reference frame that is moving with the mean flow. This choice of reference frame allows the application of periodic boundary conditions to the fluctuating velocity components and the use of a highly accurate spectral scheme for the spatial discretization. However, as time is advanced, the reference frame becomes more and more skewed and a regridding of the computational domain using the periodic structure of the velocity components is required. This regridding procedure introduces aliasing errors that are removed in direct numerical simulation. This study addresses the application of this approach to large-eddy simulation of turbulence in uniform shear flow. Results are compared between direct numerical simulation and large-eddy simulation

Large-Eddy Simulation of Homogeneous Shear Flows With Several Subgrid-Scale Models

In this article, large eddy simulation is used to simulate homogeneous shear flows. The spatial discretization is accomplished by the spectral collocation method and a third-order Runge–Kutta method is used to integrate the time-dependent terms. For the estimation of the subgrid-scale stress tensor, the Smagorinsky model, the dynamic model, the scale-similarity model and the mixed model are used. Their predicting performance for homogeneous shear flow is compared accordingly. The initial Reynolds number varies from 33 to 99 and the initial shear number is 2. Evolution of the turbulent kinetic energy, the growth rate, the anisotropy component and the subgrid-scale dissipation rate is presented. In addition, the performance of several filters is examined