Onset of hydrothermal instability in liquid bridge: experimental benchmark

The experimental results from nine benchmark test cases conducted by five different groups are presented. The goal of this study is to build an experimental database for validation of numerical models in liquid bridge geometry. The need arises as comparison of numerical results with a single experiment can lead to a large discrepancy due to specific experimental conditions. Perfectly conducting rigid walls and, especially, idealized boundary conditions at the free surface employed in numerical studies are not always realized in experiments. The experimental benchmark has emphasized strong sensitivity of the threshold of instability to the liquid bridge shape. A clear distinction should be made between results belonging to the different disturbance patterns, i.e. different wave numbers. The results of benchmark contributors are in a satisfactory agreement when they are associated with the stability branch with an identical wave number. In this case the discrepancy of the results for determination of the critical parameters is about +-15%-18% and they can be used for the validation of numerical models.