Two way coupled hypersonic fluid structure interaction simulations with Eilmer

Fluid Structure Interactions (FSI), if not managed appropriately are known to have contributed to the loss of several aerospace vehicles. As done for the X-43, FSI can be designed-out by making structures sufficiently rigid and by providing appropriate damping. In hypersonic cruise vehicles, this strategy is not applicable as stringent weight limits and large thermal loads result in structures with reduced stiffness [12]. Thus, the accurate simulation and prediction of FSI are essential to allow for the most effective design. In hypersonics, aeroelastic effects can result in rapid variations in pressure and thermal evolutions. The level of coupling between fluid and structure is typically is strong or two-way, which means that CFD and FEM solvers have to continuously exchange information in terms of nodal forces and displacement in order to produce an accurate solution. In this paper we present details of a fast implementation and first results of a FEM solver in the Eilmer CFD solver. Details are provided on the formulation of the structural solver, the fluid solver to appropriately account for the deforming boundaries, and the coupling approach. The results show that the simulations are in broad agreement with experimental data, but that an off-set exists in response frequency and amplitude. The resulting capability, with its ability to conduct time–accurate FSI simulations is a good tool to further investigate the underlying effects driving hypersonic FSI

High Frequency of Endothelial Colony Forming Cells Marks a Non-Active Myeloproliferative Neoplasm with High Risk of Splanchnic Vein Thrombosis

Increased mobilization of circulating endothelial progenitor cells may represent a new biological hallmark of myeloproliferative neoplasms. We measured circulating endothelial colony forming cells (ECFCs) in 106 patients with primary myelofibrosis, fibrotic stage, 49 with prefibrotic myelofibrosis, 59 with essential thrombocythemia or polycythemia vera, and 43 normal controls. Levels of ECFC frequency for patient's characteristics were estimated by using logistic regression in univariate and multivariate setting. The sensitivity, specificity, likelihood ratios, and positive predictive value of increased ECFC frequency were calculated for the significantly associated characteristics. Increased frequency of ECFCs resulted independently associated with history of splanchnic vein thrombosis (adjusted odds ratio = 6.61, 95% CI = 2.54–17.16), and a summary measure of non-active disease, i.e. hemoglobin of 13.8 g/dL or lower, white blood cells count of 7.8×109/L or lower, and platelet count of 400×109/L or lower (adjusted odds ratio = 4.43, 95% CI = 1.45–13.49) Thirteen patients with splanchnic vein thrombosis non associated with myeloproliferative neoplasms were recruited as controls. We excluded a causal role of splanchnic vein thrombosis in ECFCs increase, since no control had elevated ECFCs. We concluded that increased frequency of ECFCs represents the biological hallmark of a non-active myeloproliferative neoplasm with high risk of splanchnic vein thrombosis. The recognition of this disease category copes with the phenotypic mimicry of myeloproliferative neoplasms. Due to inherent performance limitations of ECFCs assay, there is an urgent need to arrive to an acceptable standardization of ECFC assessment

Proceedings of the 21st Australasian Fluid Mechanics Conference

This work discusses the design and implementation of closeproximityradiative heaters for aerothermoelastic experimentsin short-duration hypersonic facilities. The radiators areemployed to selectively heat a compliant panel both to aspecific temperature and to impose a prescribed thermal spatialdistribution. Analytical and numerical models are used todemonstrate the performance of these radiators. The analyticalstudy shows that the temperature of the test panel is primarily afunction of the panel thickness and the proximity of the heater.A 3D finite element study confirmed these predictions andfound that reasonable temperature uniformity could be achievedon the compliant panel (DT < 60 K for Tmax = 550 K) forpractical arrangements. FEM simulations also demonstratedthat non-uniform temperature distributions can be prescribed onthe panel through use of a nonuniform heater but that thesedistributions are smeared both by thermal conduction in thepanel and radiative crosstalk in the panel-heater gap

Proceedings of the 21st Australasian Fluid Mechanics Conference

This work discusses the design of a panel flutter experiment in aMach 5.8 free-piston compression-heated Ludwieg tube. Smalltest duration, low freestream pressure and limited space availablewithin the coreflow have driven the choice of boundaryconditions, material and panel geometry. The test piece is a 100mm long and 40 mm wide aluminium panel. The panel boundarycondition is clamped-free-clamped-free, with the free edgesparallel to the flow direction. The aerodynamic load can be variedby changing the inclination of the panel with respect to thefreestream. The pressure in the cavity underneath the panel isreproduced passively by channelling the external flow and creatinga recirculation region. Several strategies are employed toreduce the pressure differential between windward and cavityside of the panel. On the basis of steady-state simulations, analyticalresults and empirical laws, it is possible to state thatpanel can experience flutter during the test. Further investigationshould focus on start-up transients and temperature effects

Structural studies of the hydride-bridged iridium gold complexes 'IrHm{CH3C(CH2PPh2)(3)}{Au(PR3)}(n)'

The X-ray crystal structure of [{(triphos)H(3-x)Ir}(mu-H)(x) {Au(PR3)}][PF6] (triphos = CH3C(CH2PPh2)(3), x = 2) shows that the gold atom builds two almost equal Ir-H-Au bridges with the he'IrH3(triphos)' building block. The Ir-H-Au bridging parameters are typical of three-center-two-electron interactions. The X-ray crystal structure of [{(triphos)H(3-y)Ir}(mu-H)(y) {Au(PR3)}(2)][PF6](2) shows that each gold atom builds two Ir(mu(2)-H)Au bridges with the three hydrides of the 'IrH3(triphos)' building block; one Ir(mu(3)-H)Au-2 bridge is also present (y = 3). The relative positions of the Ir, H, Au and P atoms show that typical three-center-two-electron interactions predominate in this compound, in which there is no direct Au-Au bonding. The neutron diffraction structure of [{(triphos)Ir}(mu-H)(2){Au(PPh3)}(3)][PF6](2) confirms the earlier hypothesis that only two of the three Ir-Au edges are associated with a hydride with formation of Ir(mu(2)-H)Au bridges. The presence or absence of the latter ligand changes the Ir-Au distance only marginally, in contrast to the general trend in hydride clusters. It is shown that the formation of a 'classical' cluster in this set of compounds requires a quadrimetallic unit and the two additional electrons generated by loss of a proton from an Ir-fl bond in the trication [{(triphos)Ir (mu(2)-H)(3){Au(PR3)}(3)}(3+)