On the combined flow and structural measurements via Robotic Volumetric PTV

This study describes a novel measurement approach for combined flow and structural measurements in wind tunnels using Robotic Volumetric PTV. The measurement approach is based on the application of a particle tracking algorithm on images including flow or structure tracers, where the latter are implemented by means of fiducial markers. The main steps of the measurement procedure comprise the simultaneous acquisition of flow and structure tracers in the same images, the distinction of the tracers leading to separate flow and structure image sets, the application of Lagrangian Particle Tracking and the further post-processing, and recombination of the obtained data. The approach is applied to the fluid-structure interaction between a flexible plate with a span of 1.2 m and a periodic gust. The total measurement volume amounts approximately to 150 liters. A phase-averaged description of the fluid-structure interaction problem is presented, with the focus on the effects of the spatio-temporal averaging of the flow information. The structural displacements obtained from the PTV system are validated against a scanning vibrometer. The phase-averaged displacement of the markers is also analyzed, assessing both the validity of the phase-averaged approach and the physical coherence of their motion with respect to a structural model of the plate. It is found that Robotic Volumetric PTV is suitable for the measurement of large-scale structural displacements, while it should not be used to measure small-scale vibrations. Finally, a visualization of the combined measurement is presented, together with an analysis of the consistency between the measured structure and flow field.

Application of a Single Porous Basket as a Pier Scour Countermeasure

This paper presents a study on bridge pier protection with a single porous basket (SPB) in clear-water experiments. The SPB is a type of combined flow-altering countermeasure. The SPB was installed at a distance ahead of the protected pier. After a series of tests, the results showed that appropriate installation of the SPB was able to effectively adjust the flow pattern to reduce the down-flow motion and horseshoe vortex ahead of the pier. Dominant factors for the pier protection—considered for all tests—included the distance between the basket and pier, submerged depth of the basket, basket length, pier diameter, basket diameter, hole size, porosity, and the flow approaching angle. After evaluating these parameters through laboratory tests, the results of protection were optimized. In optimal conditions, the SPB was able to provide maximum pier protection and decrease the maximum scour depth by as much as 75.53%.

A Combined Flow Cytometric Semen Analysis and miRNA Profiling as a Tool to Discriminate Between High- and Low-Fertility Bulls

Predicting bull fertility is one of the main challenges for the dairy breeding industry and artificial insemination (AI) centers. Semen evaluation performed in the AI center is not fully reliable to determine the level of bull fertility. Spermatozoa are rich in active miRNA. Specific sperm-borne miRNAs can be linked to fertility. The aim of our study is to propose a combined flow cytometric analysis and miRNA profiling of semen bulls with different fertility to identify markers that can be potentially used for the prediction of field fertility. Sperm functions were analyzed in frozen-thawed semen doses (CG: control group) and high-quality sperm (HQS) fraction collected from bulls with different field fertility levels (estimated relative conception rate or ERCR) by using advanced techniques, such as the computer-assisted semen analysis system, flow cytometry, and small RNA-sequencing. Fertility groups differ for total and progressive motility and in the abnormality degree of the chromatin structure (P < 0.05). A backward, stepwise, multiple regression analysis was applied to define a model with high relation between in vivo (e.g., ERCR) and in vitro (i.e., semen quality and DE-miRNA) fertility data. The analysis produced two models that accounted for more than 78% of the variation of ERCR (CG: R2 = 0.88; HQS: R2 = 0.78), identifying a suitable combination of parameters useful to predict bull fertility. The predictive equation on CG samples included eight variables: four kinetic parameters and four DNA integrity indicators. For the HQS fraction, the predictive equation included five variables: three kinetic parameters and two DNA integrity indicators. A significant relationship was observed between real and predicted fertility in CG (R2 = 0.88) and HQS fraction (R2 = 0.82). We identified 15 differentially expressed miRNAs between high- and low-fertility bulls, nine of which are known (miR-2285n, miR-378, miR-423-3p, miR-191, miR-2904, miR-378c, miR-431, miR-486, miR-2478) while the remaining are novel. The multidimensional preference analysis model partially separates bulls according to their fertility, clustering three semen quality variable groups relative to motility, DNA integrity, and viability. A positive association between field fertility, semen quality parameters, and specific miRNAs was revealed. The integrated approach could provide a model for bull selection in AI centers, increasing the reproductive efficiency of livestock.

Investigation of the lateral continuity of sandstone bedsets containing hummocky cross stratifications

<p>Hummocky Cross Stratifications (HCS) are low-angle sedimentary structures found in association to sediments from the offshore transition. They are traditionally interpreted as representing storm-induced bedforms, whereby a combined flow is created including an oscillation component from storm waves and a unidirectional component from a density current, with debate on the intensity of each component. </p><p> </p><p>Here, the lateral evolution of bedsets containing HCS is investigated from field exposures. Drone images were collected from outcrops in the Moroccan Anti-Atlas from the Jbel Bani, a several hundred meters thick succession of shoreface to offshore sandstones and shales deposited during the Late Ordovician. Outcrops were targeted specifically for configurations where a vertical series of HCS sandstone bedsets occurred within silty-shale to flazer background interbeds.</p><p> </p><p>Over a few hundred meters of lateral distance, HCS beds are found to splay out into channel cuts. Outside these channel features, individual bedsets are seemingly discontinuous, either amalgamating into underlying beds or laterally passing into ripple beds. This preliminary study offers new insights into the depositional dynamics of HCS sandstone beds, feeding a long-lasting discussion over the last 50 years. </p>

Hydrodynamics of wave-current interaction at a right angle over rough beds

<p>In the present work, an investigation on the hydrodynamics of waves and currents interacting at right angle over rough beds has been carried out. The work focuses on the effects of wave motion superposed on the current steady boundary layer, and on how the oscillatory flow affects the current velocity distribution, in the presence of gravel and sand beds.</p><p>A laboratory experimental campaign on wave-current orthogonal interaction has been carried out in a shallow water basin at DHI Water and Environment (Hørsholm, Denmark).</p><p>Mean flow has been investigated by computing time- and space-averaged velocity profiles. Friction velocity and equivalent roughness have been inferred from the velocity profiles by best fit technique, in order to measure the shear stress experienced by the current mean flow.</p><p>Tests in the presence of only current, only waves and combined flow have been performed.</p><p>Instantaneous velocities have been Reynolds-averaged to obtain turbulent fluctuations time series and compute turbulence related quantities, such as turbulence intensities and Reynolds stresses.</p><p>The analysis of the mean flow revealed a complex interaction of the waves and currents combined flow. Depending on the relative strength of the current with respect to the waves, the superposition of the oscillatory flow may determine an increase or a decrease of the bottom friction experienced by the current.</p><p>The superposition of waves always induces an increase of turbulence intensity, except over gravel bed in which a decrease is observed in the very proximity of the bottom. Over gravel bed, the presence of the oscillatory flow determines a decrease of the turbulent intensity gradient, which may be related to the decrease of bottom friction observed in the mean flow analysis.</p><p>A turbulence quadrant analysis has been performed and showed that, in the presence of a lone current over a flat gravel bed, the turbulent ejection-sweep mechanism reaches parts of the water column closer to the water surface, similar to what has been observed in the turbulence intensity profiles.</p><p>The superposition of the oscillatory flow appears to induce an increment of ejections and sweeps intensity, which is associated with the shear stress increase at the bottom observed in the mean flow analysis. Moreover, a decrease of the number of ejection and sweep events has been recorded, which suggests a suppression of the ejection-sweep events alongside an enhancement of their intensity.</p>