Simulation and experimental study of sediment sampling to improve sampling technique efficiency

Abstract

Abyssal sediments are repositories of geological history and an important material basis for the study of marine biology, marine geology, paleoclimatology, and life evolution. Due to the interaction between sampler and sediments, the volumes of obtained sediment samples are commonly insufficient. Therefore, a sampling model and a numerical model calculation method are proposed to analyze the tubular sampling process in sediments. The sediments can be represented by non-Newtonian viscoplastic fluids, and sampling can be simulated using a dynamic grid technology in fluid calculation software. A three-dimensional flow field is dynamically simulated using the realizable k-ε turbulence model. The effects of structural parameters and working conditions on sample volume and sample rate were obtained. The results showed that when the drainage flow ratio is not greater than 3, drainage is sufficient. In order to improve sampling efficiency, the sample tube velocity should be maintained at 20 to 40 mm/s. By comparing the simulation to the laboratory sampling test and sea trials, absolute errors between 2.94% and 4.61% were revealed. This further verified that the sampling model can accurately reflect actual sampling scenarios. This findings provide a theoretical basis to optimize the structural design and parameters of samplers to achieve efficient sampling.