The fence experiment – full-scale lidar-based shelter observations

We present shelter measurements of a fence from a field experiment in Denmark. The measurements were performed with three lidars scanning on a vertical plane downwind of the fence. Inflow conditions are based on sonic anemometer observations of a nearby mast. For fence-undisturbed conditions, the lidars' measurements agree well with those from the sonic anemometers and, at the mast position, the average inflow conditions are well described by the logarithmic profile. Seven cases are defined based on the relative wind direction to the fence, the fence porosity, and the inflow conditions. The larger the relative direction, the lower the effect of the shelter. For the case with the largest relative directions, no sheltering effect is observed in the far wake (distances ⪆ 6 fence heights downwind of the fence). When comparing a near-neutral to a stable case, a stronger shelter effect is noticed. The shelter is highest below ≈ 1.46 fence heights and can sometimes be observed at all downwind positions (up to 11 fence heights downwind). Below the fence height, the porous fence has a lower impact on the flow close to the fence compared to the solid fence. Velocity profiles in the far wake converge onto each other using the self-preserving forms from two-dimensional wake analysis.

Experimental and Numerical Investigation on the Relative Motions of an FLNG System During Side-by-Side Operation

This paper addresses a study on the relative motions of the floating liquefied natural gas (FLNG) systems during side-by-side offloading operation through experimental method and numerical calculation method. Different filling levels and sea state conditions were adopted both in model test and numerical calculation. Model test results were used to validate the numerical models, which was then used to identify the influence of the filling levels and wave/wind directions on the relative motions of the vessels. It is indicated that the numerical calculation results show satisfactory agreement with the experimental results. More severe relative motions of vessels occur when the displacement of the LNGC reduces. When the wind and wave come from the side of the LNGC, the relative sway and heave of the two vessels become more severe while the relative surge is not affected by the shelter effect. The investigation will be beneficial to the further numeral research and FLNG side-by-side offloading operation.

The fence experiment – full-scale lidar-based shelter observations

We present shelter measurements of a fence from a field experiment in Denmark. The measurements were performed with three lidars scanning on a vertical plane downwind of the fence. Inflow conditions are based on sonic observations of a nearby mast. For fence-undisturbed conditions, the lidars' measurements agree well with those from the sonics and, at the mast position, the average inflow conditions are well described by the logarithmic profile. Seven cases are defined based on the relative wind direction to the fence, the fence porosity, and the inflow conditions. The larger the relative direction, the lower is the shelter. For the case with the largest relative directions, no shelter is observed in the far wake (distances ⪆ 6 fence heights downwind of the fence). When comparing a near-neutral to a stable case, a stronger shelter effect is noticed. The shelter is highest below ≈ 1.46 fence heights and can sometimes be observed at all downwind positions (up to 11 fence heights). Below the fence height, the porous fence has a lower impact on the flow close to the fence compared to the solid fence. Velocity profiles in the far wake converge onto each other using the self-preserving forms from two-dimensional wake analysis.

Cross-Section Model Test on Shelter Effect of Pile Jetty on Revetment

Pile jetty is a typical type of wharf in construction of port engineering and was often built in front of revetment. The reflected wave height, wave overtopping and pressure were usually reduced because of the barrier effect of upper platform and piles. Cross-section model test was in common use for the verification of structure design. The shelter effect of pile jetty on revetment was tested through cross-section wave physical model. Model scale was 1:20. The results show that the shelter effect is fairly obvious in high design water level. The reduction percentage was 33% of reflected wave height, 50% of wave overtopping and 30-50% of wave loading.

Simulated Analysis of Exploiting Space Flow Field on the Environmental Wind Influence in the Open Pit Mine

This paper focuses on computational fluid dynamics (CFD) simulation of the dynamic exploited influence of wind field in the open pit quarry. We have picked up 3 normal exploitation parameters, e.g. the exploited depth z, the type of small hills and the measured velocity u1, 7 simulated experiments have been done by software Fluent as well. In our experiments, the features of velocity field around the mine are shown, with the effects of open pit quarry, so as to analyze the changes of wind speed when it gets through this mine. To be exact, it will be possible to deduce there is negative correlation between the velocity decreased gratitude and the exploited depth. Besides, with the shelter effect of a small hill, the wind speed tends to slow down near this hill, and turn back to rise until the flow leaves the hill far away. The velocity decreasing has positive correlation with the measured velocity u1, and the reverse flow is more likely to appear with higher u1.