Journal of Cold Regions Engineering

The second log-wake law is a small change of the first log-wake law (or Coles’ log-wake law) for turbulent pipe and symmetric channel flows but makes a big difference in modeling wall-bounded turbulent flows. It has been extended to antisymmetric Couette channel flows theoretically and open channel flows empirically. A recent study of natural river flows indicates that a river velocity distribution is a superposition of a complete antisymmetric channel flow solution due to water surface shear stress and a half symmetric channel flow solution due to gravity. The objective of this research then is to test this hypothesis under the effects of ice cover and wind-induced water surface shear stress with laboratory experiments. To this end, a special experimental device was designed to simulate the effects of gravity, ice cover, and wind-induced shear stress. With this device, 236 vertical distributions of streamwise velocity were measured with a particle image velocimetry (PIV) technique under various simulated conditions of ice cover and water surface shear stress, 75 of which are plotted in this paper. All measured velocity distributions are characterized by a bowl-shaped velocity distribution with a dip phenomenon, a typical boundary layer velocity distribution, or an S-shaped velocity distribution with an inflection. All of these three distribution patterns are well described by the second log-wake law, which also agrees with real-world river flow data. Based on the second log-wake law, an innovative three-point method is proposed for river discharge measurements.

Anti-icing chemicals are used during hoar frost situations to avoid slippery road conditions. During hoar frost situations, humidity is transported from the air to the road surface. This leads to continuous dilution of the applied solution, until it eventually freezes. The protection time for a certain anti-icing application during hoar frost situations is therefore limited, and depends both on the dilution process and the freezing process. In this work, a laboratory setup has been used to study the effect of three commonly used chemicals, with different hygroscopic properties on the dilution process. An increased mass transfer rate up to 30% was seen for all chemicals in the start of the dilution process. The effect quickly diminished and after only 60 min it returned to a similar rate as without any chemical present.

Knowledge of the angle of repose of snow is significant for estimation of the rheological behavior of snow avalanches. However, at present, no comprehensive database or empirical equation is available to quantify the angle of repose for different types of snow. In this study, an attempt has been made to fill this gap by carrying out new measurements on the angle of repose of natural sieved and unsieved snow at a field research station located in Himachal Pradesh, India. The measurements were carried out using a locally developed experimental setup for the measurement of the angle of repose of snow. Analysis of the data indicates that the angle of repose of snow is determined by the snow density, temperature, and shape of the snow grains. Further, based on the data of the experiments presented in this work, a density-based empirical relation has been proposed for the estimation of angle of repose of snow.

Despite precautions taken by the operators of maintenance vehicles, insufficient visibility of winter operations vehicles causes many collisions in the United States. Numerous methods have been developed to enhance the visibility of winter operations vehicles. Although these methods have improved the visibility of winter operations vehicles, information regarding the current state of practice of these methods is crucial for the safety of winter operations vehicles, and commuters. For safer winter operations, it is critical to investigate the differences, similarities, and challenges associated with the existing methods for enhancing the visibility of winter operations. This research examines the differences, similarities, and challenges associated with these methods using a survey to collect information from state transportation agencies. Questionnaire distribution included all 50 states to investigate patterns among the states and 25 Texas Dept. of Transportation (TxDOT) districts to gather the state of practice of the operations vehicles’ visibility methods. Results of the survey brought forward the inefficiencies of some current visibility methods. For example, rear airfoils were reported to be ineffective, while many state DOTs use and maintain the airfoils despite the inefficiencies. Although a wide range of dissimilarities was found in the use of message signs and retroreflective markings, they are reported to be inexpensive and effective. It is expected that the findings of this study help transportation agencies implement more effective methods for enhancing the visibility of winter operations vehicles.