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In this case study, we examine how a citrus peel valorising company based in the Netherlands was able to adopt a circular business model while navigating regulatory, managerial, and supply chain-related barriers.

In-depth, semi-structured interviews with key personnel in the company, notes from field observations, photographs of the production process, and documents from a legal judgement served as data for this single, qualitative case study. Data were coded inductively using the in vivo technique and were further developed into four themes and a case description.

Results from our study indicate that the regulatory and political contexts in the Netherlands were critical to the company’s success. Like in the case of most fruitful industrial symbioses, partnerships founded on mutual trust and economically appealing value propositions played a crucial role in ensuring commercial viability. Collaborating with larger corporations and maintaining transparent communication with stakeholders were also significant contributing factors. Lastly, employees’ outlook towards circularity combined with their willingness to learn new skills were important driving factors as well.

In addition to expanding the scholarship on the adoption of circular business models, this research offers novel insights to policymakers and practitioners. It provides empirical evidence regarding the importance of public awareness, adaptable legislation, and harmonised policy goals for supporting sustainable entrepreneurship in the circular economy.

The adaptive reuse of heritage has the potential to socially and culturally re-signify dilapidated or suspended structures in the urban landscape. However, the scope of adaptive reuse could be broadened to include the constellation of infrastructure such as water and sewerage system, waste disposal facilities, power and communication plants and networks that support urban life but whose access – and maintenance patterns – remain the preserve of specialized technicians.

A conversation with some of the architects from the raumlabor collective involved in the Floating University Berlin project, about the stormwater detention basin of the former Berlin Tempelhof airport, provides an insight into the mechanisms by which adaptive reuse can also concern the infrastructural world in operation.

In Tempelhof's change of function from an international airport to a large abandoned urban space and then to a park, the detention basin has never ceased to function. But the subsequent process of reuse has reshaped the patterns of maintenance of the reservoir, leaving room for first non-human and then unskilled human action.

From this still overlooked reading perspective, it becomes clear how precisely flexible reuse, consisting of a constantly renegotiated interweaving of violated protocols and backward steps, allows the scope of adaptive reuse to be extended to infrastructures in operation. From secret domains of nature's transformation, they become places of openness in which to experience and better understand the entanglement of contemporary socio-ecological relations that underlie the urban condition.

This study aims to develop an experimentally validated three-dimensional numerical model for predicting different flow patterns produced with a gas dynamic virtual nozzle (GDVN).

The physical model is posed in the mixture formulation and copes with the unsteady, incompressible, isothermal, Newtonian, low turbulent two-phase flow. The computational fluid dynamics numerical solution is based on the half-space finite volume discretisation. The geo-reconstruct volume-of-fluid scheme tracks the interphase boundary between the gas and the liquid. To ensure numerical stability in the transition regime and adequately account for turbulent behaviour, the k-ω shear stress transport turbulence model is used. The model is validated by comparison with the experimental measurements on a vertical, downward-positioned GDVN configuration. Three different combinations of air and water volumetric flow rates have been solved numerically in the range of Reynolds numbers for airflow 1,009–2,596 and water 61–133, respectively, at Weber numbers 1.2–6.2.

The half-space symmetry allows the numerical reconstruction of the dripping, jetting and indication of the whipping mode. The kinetic energy transfer from the gas to the liquid is analysed, and locations with locally increased gas kinetic energy are observed. The calculated jet shapes reasonably well match the experimentally obtained high-speed camera videos.

The model is used for the virtual studies of new GDVN nozzle designs and optimisation of their operation.

To the best of the authors’ knowledge, the developed model numerically reconstructs all three GDVN flow regimes for the first time.