Abstract Thickened fluids are used in the medical management of individuals who suffer from swallowing difficulties (known as dysphagia). Recent studies show that understanding the rheological properties of thickened fluids is advantageous in designing better-controlled fluids. Whilst the rheological behavior of thickened fluids in shear deformation has been studied by several authors, studies on their extensional behavior are limited, despite their critical importance in influencing bolus flow and swallowing. Our aim in this work was to rheologically characterize extensional deformation of dysphagia fluids thickened with different types of commercial thickeners at varying concentrations using a filament stretching and break-up device. It was observed that the extensional viscosity increased and became more cohesive as the thickener concentration was increased. Additionally, it was observed that for similar shear viscosity at 50 s−1, the extensional viscosity of the fluid was dependent on the type of thickener. This study confirms that by thickening fluid with different types of thickeners, the cohesiveness of the fluid may be very different even at the same shear viscosity. Therefore, both shear and extensional rheology of thickened fluids should be considered for the management of dysphagia.

中文翻译：

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用于治疗吞咽困难的稠化液体的剪切和拉伸流变学特征

摘要 增稠液体用于治疗吞咽困难（称为吞咽困难）的个体。最近的研究表明，了解稠化流体的流变特性有利于设计更好控制的流体。虽然几位作者已经研究了稠化流体在剪切变形中的流变行为，但对其拉伸行为的研究是有限的，尽管它们在影响团流和吞咽方面至关重要。我们在这项工作中的目标是使用细丝拉伸和分解装置，以流变学表征用不同浓度的不同类型的商业增稠剂增稠的吞咽困难液体的拉伸变形。观察到拉伸粘度随着增稠剂浓度的增加而增加并且变得更加内聚。此外，观察到对于 50 s-1 时相似的剪切粘度，流体的拉伸粘度取决于增稠剂的类型。该研究证实，通过用不同类型的增稠剂增稠流体，即使在相同的剪切粘度下，流体的内聚力也可能非常不同。因此，应考虑稠化液体的剪切和拉伸流变学来治疗吞咽困难。即使在相同的剪切粘度下，流体的内聚力也可能非常不同。因此，应考虑稠化液体的剪切和拉伸流变学来治疗吞咽困难。即使在相同的剪切粘度下，流体的内聚力也可能非常不同。因此，应考虑稠化液体的剪切和拉伸流变学来治疗吞咽困难。