Computational Fluid Dynamics (CFD) have been frequently applied to model the growth conditions in photobioreactors, which are affected in a complex way by multiple, interacting physical processes. We review common photobioreactor types and discuss the processes occurring therein as well as how these processes have been considered in previous CFD models. The analysis reveals that CFD models of photobioreactors do often not consider state-of-the-art modeling approaches. As a comprehensive photobioreactor model consists of several sub-models, we review the most relevant models for the simulation of fluid flows, light propagation, heat and mass transfer and growth kinetics as well as state-of-the-art models for turbulence and interphase forces, revealing their strength and deficiencies. In addition, we review the population balance equation, breakage and coalescence models and discretization methods since the predicted bubble size distribution critically depends on them. This comprehensive overview of the available models provides a unique toolbox for generating CFD models of photobioreactors. Directions future research should take are also discussed, mainly consisting of an extensive experimental validation of the single models for specific photobioreactor geometries, as well as more complete and sophisticated integrated models by virtue of the constant increase of the computational capacity.

Microstructured optical fibers (MOFs) achieve their desired performance via a pattern of holes that run trough the whole length of the fiber. The variation of the hole pattern allows the production of a variety of optical effects. However, the cross-sectional hole structure can be different from that designed in the preform, due to the combined effects of surface tension and internal pressure. The present paper focuses on the comparison between experiments and numerical calculation of a six hole-optical fiber taking into account the effects of surface tension and internal hole-pressure, since those are of essential importance during drawing. It is shown that the numerical computations deliver reliable results for practical applications and can be used as a predictive tool for fiber development, as long as the inner pressure or the temperature do not exceed too high values.

We study incipient motion of single beads on regular substrates made of spherical particles of a different size in steady shear flow at small particle Reynolds numbers. We cover a large range of sizes: from small beads that are highly shielded from the shear flow by the substrate spheres, and hence, are susceptible to the flow through the interstices of the substrate, to beads fully exposed to the flow, where the substrate rather acts like roughness of an otherwise flat surface. Numerical and experimental studies agree within measurement uncertainty. To describe the findings, we extend a recently derived model for particles of equal size which was validated over a wide range of substrates [Agudo et al., “Shear-induced incipient motion of a single sphere on uniform substrates at low particle Reynolds numbers,” J. Fluid Mech. 825, 284–314 (2017)]. The extended model covers the entire spectrum of size ratios, where the critical Shields number varies from about zero to infinity. The model properly describes the numerical and experimental data. For well exposed beads, we find a scaling law between the critical Shields number and the size ratio between mobile bead and substrate spheres with an exponent of −1.

Microstructured optical fibres (MOFs) are fibres that contain an array of air holes that runs through the whole fibre length. The hole pattern of these fibres can be customized to manufacture optical devices for different applications ranging from high-power energy transmission equipment to telecommunications and optical sensors. During the drawing process, the size of the preform is greatly scaled down and the original hole pattern result might be modified, potentially leading to unwanted optical effects. Because only a few parameters can be controlled during the fabrication process, mathematical models that can accurately describe the fibre drawing process are highly desirable, being powerful predictive tools that are significantly cheaper than costly experiments. In this manuscript, we derive a new asymptotic energy equation for the drawing process of a single annular capillary and couple it with existing asymptotic mass, momentum, and evolution equations. The whole asymptotic model only exploits the small aspect ratio of a capillary and relies on neither a fitting procedure nor on any empirical adjustable parameters. The numerical results of the simplified model are in good accordance with experimental data available in the literature both without inner pressurization and when internal pressure is applied. Although valid only for annular capillaries, the present model can provide important insights towards understanding the MOF manufacturing process and improving less detailed approaches for more complicated geometries.

Seafood and marine biomass are highly perishable due to their high-water activity, polyunsaturated fatty acids, and susceptibility to microbial and enzymatic spoilage. Conventional thermal preservation extends shelf-life but often compromises texture, nutritional quality, and consumer acceptability. These limitations underscore the increasing importance of non-thermal technologies, particularly pulsed electric field (PEF) processing, which can preserve fresh-like attributes while enhancing sustainability. However, applications of PEF in marine biomass processing remain fragmented, creating a need for a focused and critical review. This study addresses that gap by systematically synthesizing literature from the last decade on PEF applications in seafood and marine biomass. The review examines PEF’s role in enhancing mass transfer and brining efficiency, extending shelf-life through microbial and enzyme inactivation, preserving color and nutritional attributes, improving peeling efficiency, and facilitating dewatering and drying. In addition, the valorization of by-products, such as the extraction of proteins, lipids, and polysaccharides, is critically evaluated. Challenges related to equipment robustness, conductivity constraints, electrode design, energy consumption, regulatory barriers, and consumer acceptance are also discussed. Findings indicate that PEF can significantly enhance processing efficiency, product quality, and the recovery of high-value compounds. Nonetheless, scaling to industrial levels requires standardized protocols, economic feasibility studies, and integration with complementary non-thermal methods and renewable energy sources. Overall, PEF emerges as a promising tool for sustainable seafood processing and marine biomass valorization. Its wider adoption could enhance food safety and quality while supporting circular bioeconomy practices and reducing environmental impact. Graphical abstract