Experimental and Theoretical Studies of Wet Snow Accumulation on Inclined Cylindrical Surfaces

Abstract

Wet snow accumulation on bridge cables and its shedding due to external phenomena such as rise in temperature, wind, and gravity is a serious threat to the safety of cars and pedestrians crossing the bridge. Commonly the accumulated snow on bridge cables is removed by external means such as mechanical removal or heat treatment which are expensive, time-consuming, and high-risk processes and are conducted based on little or no information available regarding the actual size and shape of the accumulated snow. In addition, cleaning of cables using the mechanical methods can potentially lead to erosion of cable materials when applied over years, resulting in enhanced surface roughness and potentially increased wet snow/ice accumulation during future precipitation events, and sometimes might require replacement of cable stays, which is an extremely costly and complicated task. Optimizing the number of mechanical cleaning procedures such as chain release through predicting the shape and thickness of the accumulated snow on the cable stays reduces the cost, time, and risk associated with the process. In this study, wet snow accumulation on torsionally rigid inclined cylinders of high-density polyethylene (HDPE) has been studied experimentally and numerically. A 2-D numerical model has been developed utilizing weather data to predict the thickness and the shape of the accumulated wet snow on inclined cylindrical surfaces. Outdoor experiments were also conducted to measure the density and thickness of accumulated snow, while monitoring the weather data real time. Overall, snow density was found to be linearly increasing with an increase in wind velocity, during snow precipitation. The maximum thickness and shape of the accumulated snow on cables obtained from the numerical model were found to be in good agreement with the outdoor experimental data. This work aims to provide a mean for prediction of snow accumulation on surfaces for optimizing the efficiency of the costly and high-risk snow removal procedures.

Active prevention of snow accumulation on cameras of autonomous vehicles

“…where �� ⃗ U is the wind velocity, (kg∕m 3 ) is the density of the continuous medium, which can be air, , Γ , S are the dependent variable, diffusion coefficient, and the source term, respectively (see Supporting Information, Table S1 for details) [28]. The inlet and outlet of the computational domain were assumed as velocity inlet and pressure outlet with zero-gauge pressure, respectively.…”

“…Previously, extensive numerical and experimental research has been carried out to examine snow accumulation on overhead structures such as power transmission lines [25][26][27][28]. One of the utmost important parameters in numerical modeling of snow accumulation on surfaces is collision efficiency of snow grains ( 1 ) , impacting the extent of snow accumulation on the object [29][30][31][32][33].…”

“…However, it has been observed that by decreasing the density or the size of the snow grains, the snow grains do not go through straight lines and some pass by the object [30]. Therefore, numerical and experimental studies have been carried out to examine the effects of the density, size, and velocity of the snow grains, and the geometry of the object on the trajectory of the snow grains [28,[35][36][37]. The results of these studies have revealed that by increasing the density, size, and velocity of snow grains, they possess higher inertia force and are not prone to follow the air streamlines around the object.…”

“…The results of these studies have revealed that by increasing the density, size, and velocity of snow grains, they possess higher inertia force and are not prone to follow the air streamlines around the object. In addition, it has been shown that the snow grains that are moving toward bigger objects experience higher drag forces when compared to their inertia forces, being inclined to follow the air streamlines without colliding to the object [28].…”

Delayed Frost Growth on Nanoporous Microstructured Surfaces Utilizing Jumping and Sweeping Condensates

“…Unwanted frost growth on surfaces in freezing atmospheric conditions is a safety, environmental, and economical concern. Active mechanical, thermal, and chemical antifrost techniques are energy- and time-consuming, often detrimental to the environment. , Recently, research groups have focused on optimizing passive antifrost techniques using low surface energy superhydrophobic surfaces , that delay frost nucleation or reduce the frost adhesion strength to surfaces. , Much of the focus is on condensation-frosting, , a common phenomenon in which supercooled condensate droplets freeze by interdroplet icing (ice-bridging) , because of an invading ice-wave front nucleated at the edges or surface defects (referred to as heterogenous ice nucleation) . Prevention of frost nucleation is not practical because of inherent surface defects formed during fabrication steps and/or suspended dust particles in the ambient atmosphere, which serve as nucleation sites. , Therefore, research has mostly focused on delaying the frost propagation (growth), reducing the frost surface coverage area, and enhancing defrosting efficiency. ,, In this study, defrosting efficiency is defined as the defrosted surface area per unit time (μm 2 /s).…”