Preparation of a Real Model of Nasal Cavities from Computed Tomography for Numerical Simulation

With improves in computing hardware and CFD methods, it is possible to work with more complex geometries. The aim of this study is to describe the preparation and creation of a model from CT scans for a numerical study of air flow into the nasal cavities. Research background: The influence of pituitary tumor surgery on the change of geometric proportions of the nasal cavity is investigated in cooperation with the Neurosurgical Department. Purpose of the article: In pituitary tumor surgery, the nasal cavity is used as an access route to the Sella turcica where the pituitary gland is located. Geometric changes occur during surgery. These changes in the geometry of the nasal cavities affect the air flow into the nasal cavities and the sense of the smell of the operated patients. Methods: Based on CT scans of one patient, a procedure was created for creation of models of nasal cavities before and after surgery of pituitary tumor. The open-source software 3D Slicer was used for processing CT scans. Furthermore, the model before and after surgery was modified in CAD program Autodesk Inventor and program Ansys Space Claim. Meshing and subsequent solution of the finite volume method was solved in program Ansys Fluent 2021 R1. Findings & Value added: The models were created considering the anatomical structure of the cavities and were aligned into corresponding coordinate systems. Despite of the efforts to align the planes, inaccuracies occur between the planes. However, the results are comparable

Examining the Impact of Inlet Shape on Nasal Cavity Flow Field: A Computational Investigation

In numerical calculations, entrance lengths and volumes upstream of the control volume are commonly used to steady the flow and obtain more accurate results. This paper discusses the effect of the geometrical shape of the inlet on the results of the flow field. The study presents the results of a Computational Fluid Dynamics (CFD) simulation of a real model of nasal cavity created from CT images of one patient. Furthermore, the spherical and cubic volume in front of the nostril entrance is modeled. Within the results, the flow fields are observed in planes across the entire sinus from the nostrils up to the nasopharynx. The resulting flow fields from all the three models are compared with each other. The effect of the geometric shape before the entrance to the nostrils is discussed considering the model without the modeled volume. The model created from the CT data of one patient was modified in CAD software to create differently shaped volumes in front of the nostrils. The CFD calculations were performed using Ansys Fluent 2021 R1 software