James D. Sterling

Accuracy of discrete-velocity BGK models for the simulation of the incompressible Navier-Stokes equations

Abstract The lattice Boltzmann (LB) method has been used as a Navier-Stokes CFD method since its introduction in 1988. The LB method is a Lagrangian discretization of a discrete-velocity Boltzmann equation. We introduce an alternative, fourth-order discretization scheme and compare results with those of the LB discretization and with finite-difference schemes applied to the incompressible Navier-Stokes equations in primitive-variable form. A Chapman-Enskog expansion of the PDE system predicts that the macroscopic behavior corresponds to the incompressible Navier-Stokes equations with additional ‘compressibility error’ of order Mach number squared. We numerically demonstrate convergence of the BGK schemes to the incompressible Navier-Stokes equations and quantify the errors associated with compressibility and discretization effects. When compressibility error is smaller than discretization error, convergence in both grid spacing and time step is shown to be second-order for the LB method and is confirmed to be fourth-order for the fourth-order BGK solver. However, when the compressibility error is simultaneously reduced as the grid is refined, the LB method behaves as a first-order scheme in time.

Continuous-Flow, Rapid Lysis Devices for Biodefense Nucleic Acid Diagnostic Systems

Two mechanical lysis devices have been developed as compact, robust components to provide rapid sample preparation for nucleic acid diagnostic systems. One such component, known as the Micro Bead-Beater™ (μBB™, BBTM, Claremont BioSolutions, Upland, CA), is a compact device that is capable of ultrarapid lysis (>90% lysis in 30 s) of micro volumes (<80 μL) ofBacillus spores in a continuous-flow format or in a disposable single-tube format. The μBB is also capable of processing much larger volumes of solutions containing spores or vegetative cells using a continuous-flow mode. A second mechanical lysis device designed as a disposable component is the microfluidic bead blender, which uses a small electric motor to spin vanes within the bead-laden solution. DNA quantification results using dsDNA-binding fluorescence dyes and real-time PCR are presented, comparing the lysis of Bacillus subtilis spores using the μBB™ with other well-known lysis techniques. Nanoscale imaging results obtained using scanning electron microscopy and transmission electron microscopy on B. subtilis spores lyzed using the μBB™ are also presented

Influence of formation processes on oblique detonation wave stabilization

In this article we report steady, two-dimensional, inviscid solutions for the near field and far field of a supersonic reactive flow over a variable-double-ramp geometry/The incident shock wave compresses and heats the reactants that will combust after flowing some induction length* Upon reaction, a detonation wave forms and intersects the leading wave at some distance from the ramp surface. In this article, reaction-polar diagrams are developed and the detonation branch solutions are used to investigate the wave interaction processes that may lead to a steady three-wave structure. By considering this formation process new oblique detonation wave stabilization criteria based on the freestream conditions and ramp geometry are provided.

Laboratory Automation Curriculum at Keck Graduate Institute

A novel curriculum in laboratory automation and high-throughput technologies has been developed at the Keck Graduate Institute (KGI) over the past five years as part of the professional masters degree program in applied life sciences. The goal of this curriculum has been four-fold: (1) motivate study by describing the need for automation through several example problems in combinatorial biological discovery, (2) provide elements of fundamental engineering science that are required for the development of the technologies and tools that enable automation, (3) provide opportunities for the students to see and use state-of-the-art instruments, learn about existing industry standards, and to visit integrated laboratories that perform high-throughput research, and (4) introduce scientific discoveries and new technologies that could have future impact on laboratory automation and discuss current trends, and project future trends in this field.

LabEvolution: What's the Next Mutation?

As an organization focused on the application of science to the automation of science, ALA seeks to create an autocatalytic ecosystem where technology providers and technology users compete and collaborate. In some sense, we are creating the primordial ooze from which new systems of discovery science will emerge. It is our emphasis on informatics, tying together automation systems with the data that they generate, that distinguishes the field of laboratory automation from traditional methods of hypothesis-driven science and the more recent discovery science.