Gaojie Liu and Zhaoli Guo
The purpose of this paper is to investigate, numerically, the effects of the Prandtl number on the mixing process in two‐dimensional Rayleigh‐Taylor instability of incompressible…
Abstract
Purpose
The purpose of this paper is to investigate, numerically, the effects of the Prandtl number on the mixing process in two‐dimensional Rayleigh‐Taylor instability of incompressible and miscible fluids.
Design/methodology/approach
The simulations are carried out based on a double‐distribution‐function lattice Boltzmann method in which the Prandtl number can be adjusted.
Findings
The simulations reveal that the mixing‐zone grows inversely with increasing Prandtl number, but the processes of Rayleigh‐Taylor instability are nearly identical in terms of a dimensionless time as the Prandtl number ranges from 0.1 to 10. The symmetric property of the mixing‐zone is also studied, which is found to be closely dependent on the symmetry of the initial perturbations.
Originality/value
The results here show that the growth of the mixing‐zone is related to the Prandtl number, whereas most previous studies have been focused on the relationship between the growth of the mixing zone and time with a constant Prandtl number.
Details
Keywords
Fei Shang, Bo Sun and Dandan Cai
The purpose of this study is to investigate the application of non-destructive testing methods in measuring bearing oil film thickness to ensure that bearings are in a normal…
Abstract
Purpose
The purpose of this study is to investigate the application of non-destructive testing methods in measuring bearing oil film thickness to ensure that bearings are in a normal lubrication state. The oil film thickness is a crucial parameter reflecting the lubrication status of bearings, directly influencing the operational state of bearing transmission systems. However, it is challenging to accurately measure the oil film thickness under traditional disassembly conditions due to factors such as bearing structure and working conditions. Therefore, there is an urgent need for a nondestructive testing method to measure the oil film thickness and its status.
Design/methodology/approach
This paper introduces methods for optically, electrically and acoustically measuring the oil film thickness and status of bearings. It discusses the adaptability and measurement accuracy of different bearing oil film measurement methods and the impact of varying measurement conditions on accuracy. In addition, it compares the application scenarios of other techniques and the influence of the environment on detection results.
Findings
Ultrasonic measurement stands out due to its widespread adaptability, making it suitable for oil film thickness detection in various states and monitoring continuous changes in oil film thickness. Different methods can be selected depending on the measurement environment to compensate for measurement accuracy and enhance detection effectiveness.
Originality/value
This paper reviews the basic principles and latest applications of optical, electrical and acoustic measurement of oil film thickness and status. It analyzes applicable measurement methods for oil film under different conditions. It discusses the future trends of detection methods, providing possible solutions for bearing oil film thickness detection in complex engineering environments.