Numerical Study of the Transport Process of Shallow Heat Carried by Turbidity Currents in Deep-Sea Environments

Turbidity currents often originate from relatively high-temperature water bodies near the coast of the upper continental shelf. Turbidity currents are the main carriers that transport land sediments to the deep sea. Their impact on heat exchange and material transport in the deep-sea ecosystem is receiving more attention. However, presently, there are few studies on heat transport by turbidity currents. This article presents a coupled model of multiphase flow and heat transfer through laboratory experiments and numerical simulations. The effects of sediment particle size, density, and Froude number on the characteristics of turbidity current heat transfer are analyzed, and the heat flux carried by turbidity currents transporting upper-layer heat into the deep sea is reproduced. The results indicate that turbidity currents are carriers of shallow heat into the deep sea. The temperature structure within turbidity currents follows a Gaussian function and can effectively preserve heat. The efficiency of the long-distance transport of heat carried by turbidity currents is negatively correlated with sediment particle size and the velocity of turbidity currents, and positively correlated with sediment concentration. Turbidity current heat shock events in the future may have significant and far-reaching impacts on deep-sea ecosystemsPlain Language Summary Turbidity currents are the main carriers of terrestrial sediment to the deep-sea plain, transporting large amounts of water and sediment along the seabed to the deep sea. Water temperature is a crucial environmental factor, and aquatic species highly depend on specific thermal conditions for effective reproduction. High-temperature turbidity currents originating from shallow waters pose a risk of "thermal shock" to the water environment along their path, the extent and scope of which are not yet clear. In this study, a new coupled model of multiphase flow and heat transfer is established through laboratory experiments and numerical simulations, providing an opportunity to estimate the heat flux carried by turbidity currents into the deep sea in the marine environment. We found that turbidity events generated by high-density river inflows into the sea can carry most of their own heat into the deep sea and significantly affect the temperature of the environmental water along the path. This, in turn, helps to understand the process of turbidity currents carrying upper-layer heat into the deep sea, which is an essential part of the global system of heat transport and cannot be ignored