GPU-accelerated large-eddy simulation of ship-ice interactions

This paper reports on the applicability of the Lattice Boltzmann based free surface flow solver elbe to the simulation of complex ship-ice interactions in marine engineering. In order to model the dynamics of these colliding rigid multi-body systems, elbe is coupled to the ODE physics engine. First, basic validations of the ODE collision and friction models are presented, particularly focusing on interacting triangle meshes that later will serve to describe the ice floes. Then, the basic methodology and initial validation of the fluid-structure coupling of elbe and ODE is presented. Finally, performance is addressed: As elbe uses graphics processing units (GPUs) to accelerate the numerical calculations, the coupled numerical tool allows for investigations of ship-ice interactions in very competitive computational time and on off-the-shelf desktop hardware

Cancers of unknown primary origin: current perspectives and future therapeutic strategies

It is widely accepted that systemic neoplastic spread is a late event in tumour progression. However, sometimes, rapidly invasive cancers are diagnosed because of appearance of metastatic lesions in absence of a clearly detectable primary mass. This kind of disease is referred to as cancer of unknown primary (CUP) origin and accounts for 3-5% of all cancer diagnosis. There is poor consensus on the extent of diagnostic and pathologic evaluations required for these enigmatic cases which still lack effective treatment. Although technology to predict the primary tumour site of origin is improving rapidly, the key issue is concerning the biology which drives early occult metastatic spreading. This review provides the state of the art about clinical and therapeutic management of this malignant syndrome; main interest is addressed to the most recent improvements in CUP molecular biology and pathology, which will lead to successful tailored therapeutic options

GPU-accelerated LBM-VOF two-phase flow simulations with grid refinement

The contribution is devoted to a novel grid refinement technique for GPU-accelerated Lattice Boltzmann Method (LBM) dedicated to free surface flow simulations in marine applications. LBM implementations are mostly based on homogeneous isotropic Cartesian discretizations of the computational domain. Challenges occur when a refined spatial and temporal resolution is locally required. To efficiently address this demand, local grid refinement is often deployed to regions featuring small scale structures and effects to be resolved. Within the LBM the spatial and temporal discretizations are strongly coupled. Hence, LBM solvers featuring local grid refinement are suitable for the simulation of transient, turbulent and free surface flows. The present LBM involves a Volume of Fluid (VOF) strategy to model two-phase flows. Herein, the advection of a mixture volume fraction serves to advance the free-surface in time. The employed grid refinement is based on overlapping grids with different resolution. The bidirectional information exchange between the grids is managed via bi[tri]-linear interpolations for two[three]-dimensional simulations. For single-phase flows this synchronisation step comprises the exchange of LBM specific variables solely. When attention is directed to two-phase flows, the inter- grid coupling of the mixture fraction poses a special algorithmic problem. The suggested coupling approach is based on a Piecewise Linear Interface Construction (PLIC) method. Accordingly, the information about the surfaces orientation and position is employed to compute the fill level more accurate within the overlapping regimes. Examples included refer to two- and three-dimensional test cases and reveal that the proposed method is able to reproduce accurate results at fairly moderate computational effort

Validation of the GPU-accelerated CFD solver ELBE for free surface flow problems in civil and environmental engineering

This contribution is dedicated to demonstrating the high potential and manifold applications of state-of-the-art computational fluid dynamics (CFD) tools for free-surface flows in civil and environmental engineering. All simulations were performed with the academic research code ELBE (efficient lattice boltzmann environment, http://www.tuhh.de/elbe). The ELBE code follows the supercomputing-on-the-desktop paradigm and is especially designed for local supercomputing, without tedious accesses to supercomputers. ELBE uses graphics processing units (GPU) to accelerate the computations and can be used in a single GPU-equipped workstation of, e.g., a design engineer. The code has been successfully validated in very different fields, mostly related to naval architecture and mechanical engineering. In this contribution, we give an overview of past and present applications with practical relevance for civil engineers. The presented applications are grouped into three major categories: (i) tsunami simulations, considering wave propagation, wave runup, inundation and debris flows; (ii) dam break simulations; and (iii) numerical wave tanks for the calculation of hydrodynamic loads on fixed and moving bodies. This broad range of applications in combination with accurate numerical results and very competitive times to solution demonstrates that modern CFD tools in general, and the ELBE code in particular, can be a helpful design tool for civil and environmental engineers

Nuclear lamin stiffness is a barrier to 3D migration, but softness can limit survival

Lamin-A provides stiff resistance to cell migration Harada et al. describe how nuclear lamins affect the ability of migrating cells to squeeze through tissues and survive the resulting stress. Migrating cells must maneuver their large and chromatin-packed nuclei through tiny gaps in the surrounding tissue. A- and B-type lamins assemble in the nuclear periphery and help determine the organelle’s mechanical properties, but whether these proteins affect cell migration is unclear. Harada et al. tested the role of lamin-A in several different cell types. Partially reducing lamin-A levels enhanced the ability of cells to move through extracellular matrix containing small, 3-μm pores, whereas overexpressing the protein inhibited cell migration. Cells that expressed stoichiometrically high amounts of lamin-B were particularly sensitive to changes in lamin-A levels. The researchers found that nuclei containing low amounts of lamin-A were softer, allowing them to squeeze through tiny pores and—due to the spring-like properties of lamin-B—return to their normal shape on the other side. In contrast, high lamin-A levels made nuclei stiff and harder to maneuver, a property that could help keep mesenchymal stem cells, which express large amounts of lamin-A, anchored in their niche. Nuclei can be too soft for their own good, however. Cells experience stress as they migrate through tissues, occasionally resulting in apoptosis. Cells lacking lamin-A were less resistant to stress and more prone to death, possibly because the