Journal of the Indian Institute of Science最新文献

Understanding and predicting multiphase flows is of great relevance due to the ubiquitous nature of such flows in both nature and in many industrial applications. Rapid development of high speed computers and problem-specific algorithms in the last 2 decades has enabled the study of multiphase flows through numerical simulations. In this paper, we give a brief overview of different methods used in direct numerical simulations of two-phase flows. In particular, we focus on the volume of fluid (VOF) method used for locating and advecting the interface. VOF method is a mesh based interface capturing method in which a scalar function called void fraction field (which is the ratio of tracked fluid to the cell volume) is advected in order to track the interface position. A geometric VOF algorithm is detailed in this work. which strikes a balance between accuracy, ease of implementation and volume conservation on a structured grid. Another challenge in two-phase flow simulations is the inclusion of surface tension forces accurately. Here, we give a brief overview of Eulerian surface tension models and detail an approach balancing computational cost, curvature estimation and imposed timestep restriction. Finally, we discuss the most recent advances in VOF methods and outline the various numerical challenges we expect to encounter.

The design of micro aerial vehicles has been long inspired by biological flyers such as birds and insects. The aerodynamic principles of flapping wing flights are complex due to the rapid wing motion and the inherent complex vortex dynamics. Several experimental and numerical investigations have been carried out in the past decades to uncover the mechanisms responsible for the improved aerodynamic capability of flapping wings. This paper provides an overview of the aerodynamics of flapping insect wings. After providing a brief overview of the aerodynamics of a single wing, we discuss how the vortex dynamics are altered in the case of tandem wings. A significant challenge to designing a stable MAV is the environmental effects stemming from the gust and ground presence. In this paper, we present how the force generation is altered due to such effects. Moreover, we point out unsolved research questions on insect flight whose answers could greatly help to improve the design of flapping wing MAVs.

In this paper, we systematically review interface-driven mesh adaptation procedures for the phase-field modeling of fluid–structure interaction problems. One of the popular ways of handling fluid–structure interaction problems involving large solid deformations is the fully Eulerian approach. In this procedure, we use a fixed computational grid over which a diffused interface description can be used to evolve the fluid–structure boundary. The Eulerian solid representation and a diffuse interface method necessitate the use of adaptive mesh refinement to achieve reasonable accuracy for the problem at hand. We explore the usage of mesh refinement techniques for such FSI problems and focus specifically on interface-driven adaptivity. We present comparisons among various error indicators for the adaptive procedure of the unstructured mesh. We finally explore some possible future directions and challenges in the field.

William Morton Wheeler (1865–1937) was among the greatest experts on ants and his influence on the field of sociobiology, along with that of his academic grandson E.O. Wilson, is second to none. In 1923, Wheeler published his landmark book “Social Life Among the Insects” (Wheeler in Social Life among the Insects, Haracourt, Brace, New York, 1923), which marked the beginning of the modern study of insect societies. In this centenary year of its publication, we are honoured and proud to pay tribute to William Morton Wheeler.

Hymenopterans present a fascinating diversity of social organisation, from solitary individuals building unprotected nests like the potter wasps to the very complex and highly organised societies of honey bees and most ants. A large number of paper wasps have intermediate levels of social complexity, and are designated as primitively eusocial, as they lack a morphologically distinct queen caste. Nevertheless, they have behaviourally distinct queens and workers, and are excellent model systems for understanding the intermediate steps in the process of social evolution, from solitary to complex social systems. Of the many facets of social organisation, the regulation of work in the colony and the establishment and maintenance of reproductive monopoly are the two aspects that are the most intriguing to sociobiologists. Ropalidia marginata and Ropalidia cyathiformis are two species of closely related paper wasps that are found in peninsular India, in the same habitat, and have much overlap in their ecology and ethology. However, this duo is also an interesting study in contrast in several aspects of social behaviour. Hence, together, they present an excellent opportunity for comparative study, to identify crucial steps in social evolution. In this article, we provide an overview of a series of studies that have been conducted by Prof. Raghavendra Gadagkar and his team over 4 decades at the Indian Institute of Science, Bengaluru, to unravel the evolutionary tale that these two species together elucidate.

This article provides an overview of the importance of outreach for biodiversity conservation and the author’s personal journey in promoting awareness about ants and their natural history, and conservation amongst the general public on ants. It also highlights the importance of educational materials such as books and posters which are important tools for outreach programmes. The article also highlights steps including Open Science that can be taken to increase outreach activities and contribute to the body of knowledge on social insects.