One-dimensional Model for Fluids of Third-grade in Tubes with Constant Radius

Our goal in this paper is to extend previous results obtained for Newtonian and secondgrade fluids to third-grade fluids in the case of an axisymmetric, straight, rigid and impermeable tube with constant cross-section using a one-dimensional hierarchical model based on the Cosserat theory related to fluid dynamics. In this way we can reduce the full threedimensional system of equations for the axisymmetric unsteady motion of a non-Newtonian incompressible third-grade fluid to a system of equations depending on time and on a single spatial variable. Some numerical simulations for the volume flow rate and the the wall shear stress are presented.

Specific shear-dependent viscoelastic third-grade fluid model

A specific modified constitutive equation for a third-grade fluid is proposed so that the model be suitable for applications where shear-thinning or shear-thickening may occur. For that, we use the Cosserat theory approach reducing the exact three-dimensional equations to a system depending only on time and on a single spatial variable. This one-dimensional system is obtained by integrating the linear momentum equation over the cross-section of the tube, taking a velocity field approximation provided by the Cosserat theory. From this reduced system, we obtain the unsteady equations for the wall shear stress and mean pressure gradient depending on the volume flow rate, Womersley number, viscoelastic coefficient and flow index over a finite section of the tube geometry with constant circular cross-section.

Interdisciplinarity and Design Conceptualisation: Contributions from a Small-Scale Design Experiment

Literature emphasises the sparse research focused in collaborative and open approaches in the design conceptualisation stage, also known as the Fuzzy Front-End (FFE). Presently, the most challenging discussion arising from this specific field of research lies in understanding on whether or not to structure the referred conceptual stage. Accordingly, the established hypothesis behind this study sustains that a structured approach in the FFE would benefit the interdisciplinary dialogue. Therefore, two objectives support this study: to understand the benefits of an interdisciplinary approach in the FFE, and to test one proposed model for this conceptual stage. By means of a small-scale design experiment, this paper pretends to give additional contributions to this area of research, in the context of new product development (NPD). The general research supporting this specific study aims to conceptualise in the area of newly and futuristic aircraft configurations. Hence, this same topic based the conceptualisation process in the conducted ideation sessions, which are conducted by five different teams of three elements each. The results of the different ideation sessions reinforce the contemporary paradigm of Open Innovation (OI), which is based in trust and communication to better collaborate. The postulated hypothesis for this study is partially validated as teams testing the proposed and structured model generally consider that its usage would benefit the integration of different disciplines. Besides, a general feeling that a structured approach integrates different perspectives and gives creativity a focus pervades. Nevertheless, the small-scale of the design experiment attributes some limitations to this study, despite giving new insights in how to better organise coming and more sustained studies. Interestingly, the importance of sketching as an interdisciplinary means of communication is underlined with the obtained results.