Numerical analysis of a clinically-extracted vascular tissue during cryo-freezing using immersed boundary method

• Model compares well with experiment data with a maximum error of 3.04%.
• Study cryofreezing with clinically-extracted vascular via immersed boundary method.
• Incorporation of nanoparticles markedly impacts tissue temperature profiles.
• Blood vessel complexity markedly impacts tissue temperature profiles.

In this paper, the effects of the blood vessel structure and injected nanoparticles on the cryo-freezing of a clinically-extracted vascular tissue are numerically investigated. A hybrid two-dimensional (2D) finite difference analysis combined with immersed boundary method has been developed to accurately simulate the cryo-freezing process. Based on the measured experimental temperature field, the numerical results compared well with the experimental data with a maximum error of 3.04%. This improved cryo-freezing model is able to significantly simplify the mesh generation process at the boundary resulting in improved computational efficacy. For simulating the temperature profile of a tumor that is sited in a dominantly vascularized tissue, our model is able to capture with ease the thermal effect at junctions of the blood vessels. We also analyzed the effects of blood vessel complexity and nanoparticles on iceball deformation which cannot be easily quantified through clinical experiments. Results indicated that the thermal effects of large blood vessels, especially for a more complex blood vessel boundary, remarkably affect the temperature and deformation distributions. In addition, the numerical results showed that, the inclusion of nanoparticles enlarged the cryo-freezing area as they enhance the thermal conductivity and thermal capacity of tissue.