Modelling of an oscillating water column in DualSPHysics

C

Launch Environment Water Flow Simulations Using Smoothed Particle Hydrodynamics

This paper describes the use of Smoothed Particle Hydrodynamics (SPH) to simulate the water flow from the rainbird nozzle system used in the sound suppression system during pad abort and nominal launch. The simulations help determine if water from rainbird nozzles will impinge on the rocket nozzles and other sensitive ground support elements

Analog Models of Fold-and-Thrust Wedges in Progressive Arcs: A Comparison With the Gibraltar Arc External Wedge

The timing and kinematics of the different types of structures and the associated vertical-axis rotations that permit an arcuate external wedge to acquire progressively its curved shape throughout its deformation history—known as progressive arcs—are key questions in natural cases of arcuate fold-and-thrust belts that we want to address through analog modeling. We present laboratory models of fold-and-thrust belts formed with a backstop that deforms in map view to simulate progressive arcs in a thin-skinned tectonic regime. Our setup makes use of a deformable backstop rigid enough to push from behind the initial parallelepiped but deformable in map view. This innovative design permits us to increase the amplitude of the arc indenting in the model as its radius of curvature decreases, that is, it simulates a progressive arc. Taking the Gibraltar Arc external wedge situated in the western Mediterranean to scale our models in terms of rheology, velocities, and sizes, four types of experiments were made. We varied the type of substratum (sand or silicone), the silicone thickness, and the width and length of the initial analog pack in order to test the influence of each of these parameters on the resulting fold-and-thrust belts. All experiments led to the formation of arcuate wedges where strain was partitioned into: (a) arc-perpendicular shortening, accommodated by thrusts which main structural trend is broadly subparallel to the indenter shape and with divergent transport directions, and (b) arc-parallel stretching, accommodated by normal and conjugate strike-slip faults. The normal and strike-slip faults contributed to the fold-and-thrust belt segmentation and the formation of independent blocks that rotated clockwise and counterclockwise depending on their position within the progressive arc. Our experiments allow to simulate and understand the finite deformation mode of the external wedge of the Gibraltar Arc. Accordingly, they shed light on how an arcuate fold-and-thrust belt can develop progressively in terms of structural trend and transport directions, types and distribution of the structures accommodating strain partition, and timing of vertical-axis rotations.This study was supported by projects RNM-0451, EST1/00231, CGL2017-89051-P, PGC2018-100914-B-I00, and UPO 1259543

ALMA Cycle 1 Observations of the HH46/47 Molecular Outflow: Structure, Entrainment and Core Impact

We present ALMA Cycle 1 observations of the HH46/47 molecular outflow using combined 12m array and ACA observations. The improved angular resolution and sensitivity of our multi-line maps reveal structures that help us study the entrainment process in much more detail and allow us to obtain more precise estimates of outflow properties than previous observations. We use 13CO(1-0) and C18O(1-0) emission to correct for the 12CO(1-0) optical depth to accurately estimate the outflow mass, momentum and kinetic energy. This correction increases the estimates of the mass, momentum and kinetic energy by factors of about 9, 5 and 2, respectively, with respect to estimates assuming optically thin emission. The new 13CO and C18O data also allow us to trace denser and slower outflow material than that traced by the 12CO maps, and they reveal an outflow cavity wall at very low velocities (as low as 0.2km/s with respect to the cores central velocity). Adding with the slower material traced only by 13CO and C18O, there is another factor of 3 increase in the mass estimate and 50% increase in the momentum estimate. The estimated outflow properties indicate that the outflow is capable of dispersing the parent core within the typical lifetime of the embedded phase of a low-mass protostar, and that it is responsible for a core-to-star efficiency of 1/4 to 1/3. We find that the outflow cavity wall is composed of multiple shells associated with a series of jet bow-shock events. Within about 3000AU of the protostar the 13CO and C18O emission trace a circumstellar envelope with both rotation and infall motions, which we compare with a simple analytic model. The CS(2-1) emission reveals tentative evidence of a slowly-moving rotating outflow, which we suggest is entrained not only poloidally but also toroidally by a disk wind that is launched from relatively large radii from the source.Comment: Accepted for publication in ApJ. 26 pages, 20 figure

Numerical Model of Constrained Wave Energy Hyperbaric Converter under Full-Scale Sea Wave Conditions

Funding Information: This research was funded by Fundação para a Ciência e a Tecnologia (FCT.IP) through the grant UIDB/00667/2020 (UNIDEMI). This work was also supported by the project SURVIWEC PID2020-113245RB-I00 and by the project ED431C 2021/44 “Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas”. This study forms part of the Marine Science programme (ThinkInAzul) supported by Ministerio de Ciencia e Innovación and Xunta de Galicia with funding from the European Union NextGenerationEU (PRTR-C17.I1) and European Maritime and Fisheries Fund. Funding Information: The authors acknowledge Fundação para a Ciência e a Tecnologia (FCT.IP) for its financial support through the grant UIDB/00667/2020 (UNIDEMI). This work was also supported by the project SURVIWEC PID2020-113245RB-I00 financed by MCIN/AEI/10.13039/501100011033 and by the project ED431C 2021/44 ”Programa de Consolidación e Estructuración de Unidades de Investigación Competitivas” financed by Xunta de Galicia, Consellería de Cultura, Educación e Universidade. This study forms part of the Marine Science programme (ThinkInAzul) supported by Ministerio de Ciencia e Innovación and Xunta de Galicia with funding from the European Union NextGenerationEU (PRTR-C17.I1) and European Maritime and Fisheries Fund. Publisher Copyright: © 2022 by the authors.A 2D numerical investigation of the power absorption of a constrained wave energy hyperbaric converter (WEHC) under full-scale sea wave conditions is presented. A fully non-linear numerical model DualSPHysics, based on the coupling of a smoothed particle hydrodynamics (SPH) fluid solver with a multibody dynamics solver, is used to model the interaction between wave and WEHC sub-systems. The numerical model was first validated against experimental data for a similar device, with a good accordance between PTO position and velocity. The model is then employed to study the hydrodynamics of a constrained WEHC considering several sea states, different hydraulic power take-off (PTO) damping and breakwater geometries. It is observed that the capture width ratio (CWR) is particularly sensitive to variations in the PTO damping, although the CWR absolute maximum is less sensitive considering mild variations applied to the PTO damping. Both wave height and wave period have an important effect on the CWR. The breakwater geometry is also essential for the performance of the WEHC, with a decrease in maximum CWR of about 15% for porous breakwater. These results are necessary to understand the full-scale behaviour of WEHC.publishersversionpublishe

Highly Collimated Molecular Hydrogen Jets Near IRAS 05487+0255: NIR Imaging and Spectroscopy

We present new narrow-band near-infrared images together with K band spectra of highly collimated bipolar jets close to the IRAS 05487+0255 source. The jets are located at 50" West of the Herbig-Haro 110 outflow. The jets are not visible at optical wavelengths, and therefore, do not fall into the `standard' Herbig-Haro object classification scheme. Nevertheless, they belong to an ever growing group of molecular hydrogen jets associated with YSOs which are optically undetected. The jets are very well collimated, with a length-to-width ratio of 10-20. The spectra of the jet and counter-jet in the K-band show a limited number of molecular hydrogen emission lines which makes it difficult to obtain an accurate excitation temperature. We estimate Tex = 1104+/-67 K and Tex = 920+/- 156 K for the red and blue jet components respectively. The radial velocities of the jet and counter-jet, based on the shift of the (1,0) S(1) 2.121 micron line, are -275+/- 50 km/s and 180+/- 50 km/s respectively, suggesting an angle of 30 to 45 degrees between the jet and the line of sight. The molecular hydrogen emission of the entire jet extends for at least 40" or 0.1 pc at the distance of Orion. If the flow velocity is comparable to that of the radial velocities, then the dynamical age of the system is quite short (about 500 yrs), consistent with a young jet arising from an embedded source. Entrainment in a turbulent mixing layer may explain this morphology and spectral character.Comment: 15 pages, 5 postscript figures, Accepted to the Ap