Two-equation oxygen diffusivity of apple cortex tissue for multiscales modeling of gas exchange

VERBOVEN, P; ZORRILLA, SE; JASSEN, S; NICOLAI, B

Ghent

Congreso; FOODSIM'2018; 2018

The European Multidisciplinary Society for Modelling and Simulation Technology

Atwo-equation multiscale model was developed for diffusive oxygen transport inapple cortex tissue. Effective diffusivity of oxygen in both the pore and thecell phase was computed for the 3D microstructure of Jonagold cortex.Microstructure images were obtained with high resolution X-ray CT, and used inmicroscale simulations of gas diffusion with a voxel based finite volumemethod. The effective diffusivity of the liquid phase was as expected normallydistributed, while the effective diffusivity of the gas phase showed a bimodal distribution.This was caused by the low pore connectivity of some of the 3D microstructuresas 10 out of the 16 used samples did not show any open porosity. The 3D microstructureof the apple tissue imposed a significant reduction in the gaseous diffusivity.A comparison was made with the effective tissue diffusivity of a one-equationmodel for oxygen diffusion, assuming phase equilibrium. Good correspondence wasfound between the two models for the microscale properties of the tissues used.The large variation in the equilibrium effective tissue diffusivity that was obtainedearlier could thus be explained by the variability in open porosity of applecortex tissue.