NUMERICAL STUDY OF NON-NEWTONIAN FLUID FLOWS IN Y-SHAPED STRUCTURES

Alysson Sehn¹; Vinicius da Rosa Pepe¹; Antonio Ferreira Miguel²; Flávia Zinani³; Luiz Alberto Oliveira Rocha³

¹ Universidade Federal do Rio Grande do Sul; ² Universidade de Évora; ³ Universidade do Vale do Rio dos Sinos

doi:10.20906/CPS/CILAMCE2017-0558

Resumo

Vascular and respiratory trees are complex flow systems consisting of series of large and small ducts. Although the literature reports several cases that are in accordance with Hess-Murray law, there are also some branching patterns of natural systems that deviate from this law. In this study, a numerical analysis was carried out to investigate laminar fluid flow of non-Newtonian fluids, in Y-shaped flow structures with different ratios between the sizes of parent and daughter ducts. The non-Newtonian behavior was predicted using power-law and Carreau-Yasuda models. The main parameters in the present study were the angle between the daughter ducts and the relationships between the diameters and between the lengths of the parent and daughter ducts. The performance of the branching systems was evaluated in terms of total hydraulic resistance and distribution of shear stresses. The effect of rheological parameters was also analyzed. These results were compared with analytical results obtained based on Constructal Law. We showed that the physical optimization in the tree-network design is not always given by a reduction of vessel size by a constant factor of 2−1/3. This type of study can be beneficial in the medical field, helping in the diagnosis and treatment of cardiac and circulatory diseases, such as in poor arterial formations and revascularization surgeries, as well as in the chemical industry, since most of the fluids circulating in this type of industry present non-Newtonian behavior.

Palavras-chave: Constructal design; Hess-Murray law; Y-shaped assembly; Non-Newtonian fluid