ARUP; ISBN: 978-0-9562121-5-3 - CMBBE 2012 - Cardiff University

3. MATERIALS AND METHODS
3.1 The model of semicircular canal and cupula
A model of semicircular canal was developed as a simple circle based on the CT image.
The endolymph is assumed as a compressible Newtonian fluid and the wall is assumed
to have no slipping. A model of FSI is the combination of the cupula on the fluid model.
Originally the cupula consists of several membranes, but this study modeled as 2D
shape. Material properties of cupula used in Table.1 are obtained from literature. 7
Structures was meshed by three-noded triangular element with a total of 7370 elements.
Table.1 Material properties of semicircular canal and cupula
Viscosity Modulus of Elasticity Poisson’s ratio
Endolymph 0.852 - -
Cupula - 5.4 Pa 0.48
3.2 The model of otolith in endolymph
Fig.3 Model of the semicircular canal and Cupula
The otolith is inorganic crystal which consists of calcium carbonate or calcite. The
specific gravity of otolith is about three times heavier than water. But the material
properties of otoliths are not largely important in this study and instead the weight is the
critical factor. Although the shape can be an important variable parameter, it is assumed
as circle in this study and the number of otoliths is just one.
Fig.4 Scanning electron micrograph of otoconia Fig.5 Model of otolith
The sizes of otolihts are 0.5 m to 30 m, and usually are 5~7 m. In this study it is
assumed as 0.1mm. Originally the motion of otoliths should be free as an error occur
because the mesh is broken or disappear when otoliths is in contact with wall. The
motion of otolith was assumed as falling straight to the direction of gravity at one point.
Fig. 6 represents that situation when the head suddenly bend forward.