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• The development of aerial vortex bioreactors led to interest in two-fluid or multiphase flows. • The study is related to hydrodynamics and mass transfer in vortex flows for chemical and biotechnology application. • The vortex bioreactor provides the gentle mixing of ingredients required for the efficient growth of tissue cultures. • The results are of great interest for identify the kinematic parameters of opaque media of the cultured biomaterial. Research into the flow structure in an aerial vortex bioreactor is relevant for developing the methods to grow cell cultures. It is especially important in the case when, with the culture growth in the bioreactor, such parameters of the medium as density and viscosity can significantly change, accordingly altering the characteristic flow regimes. Since the cultivated culture is not transparent in most cases, it is impossible to visually determine the flow regime. Therefore, a detailed study of the regularities of flow regimes in an aerial vortex reactor is of great fundamental and applied interest. The research was carried out in an 8.5 L universal glass aerial vortex bioreactor, with a washer freely floating on its surface and stabilizing the motion of the working fluid. The regularities of the vortex motion of the culture medium depend on its volume and the rotation intensity of the activator generating vortex motion in the air. The air vortex generated by the impeller (activator) above the liquid surface spins the working fluid and a free-floating washer. The study reveals that despite the complex configuration of the flow stabilizing device (a free-floating washer), the observed vortex structure and its dynamics with increasing flow swirl intensity coincides with the structure of a confined vortex flow in a cylindrical container for both single-fluid and immiscible two-fluid configurations. [Display omitted] [ABSTRACT FROM AUTHOR]

• Experimental study of swirling two-fluid flow in a vertical cylinder. • The rotating lid drives a steady axisymmetric circulation. • A jump of a swirl velocity at the interface is observed. • The Moffatt eddy occurs near the interface-sidewall intersection. • The results can be important for bioreactors. Recent theoretical and numerical studies predict the Moffatt eddies near the interface-wall intersection in a two-fluid flow. The current work provides the first experimental evidence of this phenomenon of fundamental interest. It also reveals a jump of the azimuthal velocity at the interface which can be important for vortex bioreactors. The rotating lid drives a two-fluid flow in a vertical cylindrical container whose other walls are stationary. Near the lid, the centrifugal force pushes the upper fluid to the sidewall thus developing its centrifugal meridional circulation. This motion drives the bulk counter-circulation and the Moffatt eddies in the lower fluid at a slow rotation. Using sunflower oil for the upper fluid, water-glycerin or alcohol-glycerin solutions for the lower fluid, and assemble averaging of PIV images allow for velocity measurement and flow visualization even in a creeping motion. This advanced experimental technique helps detect velocity jumps, occurring at the interface and the Moffatt outermost eddy. [ABSTRACT FROM AUTHOR]

The future limitation of certain types of minerals due to reduced availability and monopolization of their production requires international legal principles to forecast and respond to international environmental policy. The efficiency and complexity of mineral extraction in terms of environmental, social, governance (ESG) principles is largely determined by the level of professional competence of an extractive company. The level of professional competence of a resource extraction engineer is the equivalent of trust in the company's activities and its ability to comply with ESG principles. The paper proposes for consideration a system for determining the levels of professional competencies of the "Professional Resource Extraction Engineer" based on the "International Standards for Resource Extraction Engineers (ISREE)". Threshold requirements for additional knowledge are expected to be introduced in areas such as ethics, safety, environment and preservation of financial viability. The developed methodology and digital indicators for evaluating the activities of public extractive companies, with consideration to ESG principles and sustainable development goals (SDG), allows increasing transparency and trust in its activities of the local population. • ESG principles should set standards for limiting the use of technology and for the sustainability of the biosphere. • Environmental diplomacy, trust and indigenous participation play a dominant role in resource production. • The expertise of an engineer is determined by a balance between the interests of the investor and the results for society. • Public policy largely determines the cost and benefits of the technologies used in the extractive industry. • Digital targets or the level of state regulation are not used in assessing a company's activities against ESG principles. [ABSTRACT FROM AUTHOR]