Research on the scientific and engineering problems of porous media has drawn increasing attention in recent years. Digital core analysis technology has been rapidly developed in many fields, such as hydrocarbon exploration and development, hydrology, medicine, materials and subsurface geofluids. In summary, science and engineering research in porous media is a complex problem involving multiple fields. In order to encourage communication and collaboration in porous media research using digital core technology in different industries, the 5 ${}^{\mathrm{th}}$ International Conference on Digital Core Analysis & the Workshop on Multiscale Numerical and Experimental Approaches for Multiphysics Problems in Porous Media was held in Qingdao from April 18 to 20, 2021. The workshop was jointly organized by the China InterPore Chapter, the Research Center of Multiphase Flow in Porous Media at the China University of Petroleum (East China) and the University of Aberdeen with financial support from the National Sciences Foundation of China and the British Council. Due to the current pandemic, a hybrid meeting was held (participants in China met in Qingdao, while other participants joined the meeting online), attracting more than 150 participants from around the world, and the latest multi-scale simulation and experimental methods to study multi-field coupling problems in complex porous media were presented.

Quantitative evaluation of the effective thermal conductivity of porous media has received wide attention in science and engineering since it is a key thermophysical parameter in characterizing heat transfer properties. Based on fractal characters of tortuous capillary tubes and rough surfaces in micro-pores, we proposed a theoretical model of the effective thermal conductivity in porous media with rough surfaces. This model considers the geometrical parameters of porous media, including porosity, micro-pore fractal dimension, tortuosity fractal dimension, and relative roughness. The calculated normalized effective thermal conductivity was then validated against published experimental data. The results show good agreement between them. The influence of geometrical factors, porosity and relative surface roughness, on the effective thermal conductivity in porous media with rough surfaces are discussed and analyzed extensively.

Multiphase flow in porous media is relevant to amount of engineering processes, such as hydrocarbon extraction from reservoir rock, water contamination, CO₂ geological storage and sequestration. Pore scale modeling, as an alternative approach to lab measurement, firstly serves as an effective bridge to link the pore scale properties (pore geometry and wettability) and displacement mechanisms to continuous scale multiphase flow in porous media; and secondly allows us to determine essential flow functions, such as capillary pressure and relative permeability curves, which are required for continuous scale modeling. In the literature, three methodologies, bundle of sapillary tube modeling, direct pore scale modeling and pore network modeling, have appeared to be mostly widely adopted in the investigation of the pore-scale mechanics of fluid-fluid and fluidsolid interactions in porous media by numerical simulation. In this review article, a comprehensive review is provided to show their strengths and weaknesses and to highlight challenges that are faced in modelling of multiphase flow, key challenges include: are contact angle characterization, validation and upscale pore scale findings to core, or even field scale.