Ship-Wave Impact Generated Sea Spray. Part 1: Formulating Liquid Water Content and Spray Cloud Duration

2021 ◽  
Author(s):  
Shafiul Mintu ◽  
David Molyneux ◽  
Bruce Colbourne
Author(s):  
Shafiul A. Mintu ◽  
David Molyneux ◽  
Bruce Colbourne

Abstract When a wave impacts a ship, a cloud of water spray may form. This spray water, in cold climates, significantly contributes to the deposition of icing on the ship. Estimation of the spray flux is a first step towards predicting the marine icing. The amount of spray water, termed as liquid water content (LWC), the time of ship exposure to the spray cloud in a spray event known as spray duration, and the frequency at which the spray is generated are all important parameters required to define the spray flux. Most of the spray flux formulas found in the literature are based on field observations of small fishing vessels. Moreover, they consider meteorological and oceanographic parameters only and ignore the characteristic behaviors of the vessel. These formulas are therefore not applicable to any size and type of vessel. This paper develops methods to quantify the spray properties in terms that can be applied to vessels of any size. Formulas to estimate two crucial spray properties, LWC and spray duration, are derived based on the energy conservation principles and by non-dimensional analysis. The formulas take into account the ship’s principal particulars, its operating conditions, and the environmental parameters. The formulas are validated against full-scale field measurement from a Russian fishing trawler, MFV Narva, and a medium-size US coast guard vessel, USCGC Midgett. Reasonable agreements are found in both cases.


Sensors ◽  
2017 ◽  
Vol 17 (3) ◽  
pp. 647 ◽  
Author(s):  
Carlos Pérez Díaz ◽  
Jonathan Muñoz ◽  
Tarendra Lakhankar ◽  
Reza Khanbilvardi ◽  
Peter Romanov

1981 ◽  
Vol 27 (95) ◽  
pp. 175-178 ◽  
Author(s):  
E. M. Morris

Abstract Field trials show that the liquid-water content of snow can be determined simply and cheaply by a version of Bader’s solution method.


1994 ◽  
Vol 19 ◽  
pp. 92-96 ◽  
Author(s):  
TH. Achammer ◽  
A. Denoth

Broadband measurements of dielectric properties of natural snow samples near or at 0°C are reported. Measurement quantities are: dielectric permittivity, loss factor and complex propagation factor for electromagnetic waves. X-band measurements were made in a cold room in the laboratory; measurements at low and intermediate frequencies were carried out both in the field (Stubai Alps, 3300 m; Hafelekar near Innsbruck, 2100 m) and in the cold room. Results show that in the different frequency ranges the relative effect on snow dielectric properties of the parameters: density, grain-size and shape, liquid water content, shape and distribution of liquid inclusions and content of impurities, varies significantly. In the low-frequency range the influence of grain-size and shape and snow density dominates; in the medium-frequency range liquid water content and density are the dominant parameters. In the microwave X-band the influence of the amount, shape and distribution of liquid inclusions and snow density is more important than that of the remaining parameters.


Author(s):  
Pradyumna Challa ◽  
James Hinebaugh ◽  
A. Bazylak

In this paper, through-plane liquid water distribution is analyzed for two polymer electrolyte membrane fuel cell (PEMFC) gas diffusion layers (GDLs). The experiments were conducted in an ex situ flow field apparatus with 1 mm square channels at two distinct flow rates to mimic water production rates of 0.2 and 1.5 A/cm2 in a PEMFC. Synchrotron radiography, which involves high intensity monochromatic X-ray beams, was used to obtain images with a spatial and temporal resolution of 20–25 μm and 0.9 s, respectively. Freudenberg H2315 I6 exhibited significantly higher amounts of water than Toray TGP-H-090 at the instance of breakthrough, where breakthrough describes the event in which liquid water reaches the flow fields. While Freudenberg H2315 I6 exhibited a significant overall decrease in liquid water content throughout the GDL shortly after breakthrough, Toray TGP-H-090 appeared to retain breakthrough water-levels post-breakthrough. It was also observed that the amount of liquid water content in Toray TGP-H-090 (10%.wt PTFE) decreased significantly when the liquid water injection rate increased from 1 μL/min to 8 μL/min.


2018 ◽  
Vol 45 (17) ◽  
pp. 9323-9330 ◽  
Author(s):  
N. Küchler ◽  
S. Kneifel ◽  
P. Kollias ◽  
U. Löhnert

1994 ◽  
Vol 12 (2/3) ◽  
pp. 240-253 ◽  
Author(s):  
F. Parol ◽  
J. C. Buriez ◽  
D. Crétel ◽  
Y. Fouquart

Abstract. Through their multiple interactions with radiation, clouds have an important impact on the climate. Nonetheless, the simulation of clouds in climate models is still coarse. The present evolution of modeling tends to a more realistic representation of the liquid water content; thus the problem of its subgrid scale distribution is crucial. For a convective cloud field observed during ICE 89, Landsat TM data (resolution: 30m) have been analyzed in order to quantify the respective influences of both the horizontal distribution of liquid water content and cloud shape on the Earth radiation budget. The cloud field was found to be rather well-represented by a stochastic distribution of hemi-ellipsoidal clouds whose horizontal aspect ratio is close to 2 and whose vertical aspect ratio decreases as the cloud cell area increases. For that particular cloud field, neglecting the influence of the cloud shape leads to an over-estimate of the outgoing longwave flux; in the shortwave, it leads to an over-estimate of the reflected flux for high solar elevations but strongly depends on cloud cell orientations for low elevations. On the other hand, neglecting the influence of cloud size distribution leads to systematic over-estimate of their impact on the shortwave radiation whereas the effect is close to zero in the thermal range. The overall effect of the heterogeneities is estimated to be of the order of 10 W m-2 for the conditions of that Landsat picture (solar zenith angle 65°, cloud cover 70%); it might reach 40 W m-2 for an overhead sun and overcast cloud conditions.


Sign in / Sign up

Export Citation Format

Share Document