Drying of Corn Kernels: From Experimental Images to Multiscale Multiphysics Modeling

Pawan S. Takhar, and Shuang Zhang - Texas Tech University ; Thermo Fisher Scientific

This work demonstrated the importance and feasibility of experimental image
to simulation workflow. The workflow is successfully applied to a food processing study, where multiphysics and multiscale modeling
based on 3D experimental image reconstruction contributes to the preservation of corn, one of the major food sources for the world population.

Corn kernels have a complex structure as they are composed of a pericarp layer outside and contain hard and soft endosperm and germ components. Corn kernels are harvested around 30% moisture content on dry basis and dried to about 12% moisture content using heated air. Drying helps to lower the water activity to increase their shelf life. If the drying is not controlled properly, the kernels develop stress cracks, which makes them prone to insect and microbial damage.
To study and control the drying process, multiscale and multiphysics simulation conducted on the real corn kernel geometry is necessary. While the complex corn kernel structure make it extremely challenging to model
accurately, this paper adapted an experimental image to simulation workflow.

How Amira-Avizo Software is used

The 2D slices obtained using micro CT were reconstructed into a 3D volumetric dataset using Avizo.  A multiresolution algorithm is used by Avizo to ensure the best quality and performance that are supported by available resources on various display hardware. After appropriate filtering, automatic and interaction segmentation algorithms were adopted to segment the corn kernel into various components such as hard endosperm, soft endosperm and germ. Figure 3 demonstrates the Avizo user interface for completing this task.
The voxels of interest can be selected automatically, using thresholds or magic wand for example, or interactively using methods such as growing contour. The segmentation is a twopass workflow, separating voxel selection and voxel assignment, to ensure greatest flexibility in creating, modifying, and managing different materials. In both voxel selection and assignment, automatic and interactive tools can be used in combination. Avizo also provided semi-automatic tools such as interpolation and warping to ensure the right balance of user interactivity and automation.