The Chair of Building Physics of ETHZ uses advanced modeling and experimental methods to study the multiple physical aspects of porous materials and their interactions with fluids. At Los Alamos National Laboratory, the Earth and Environmental Sciences group is studying the physiology of trees under changing climate and developing mechanistic understanding of tree mortality during drought. We are offering a PhD Position - Microfluidics in large deformation media: transport of fluids in trees.Water/sap transport in plants is considered from a microfluidic point of view using advanced imaging techniques of natural or manufactured deformable cellular systems. In a tree, the xylem and the phloem form a continuous system from the roots to the leaves where the xylem (a dead tissue) transports water up and phloem (a living tissue) transports the sugary sap down.
Flow in the xylem is thought to passively respond to changes in pressure gradients whereas, in the phloem, the plant can control flow actively by osmotic means. Climate change may impose severely different conditions on trees which may, or not, be able to cope by modifying their regulation of liquid flow. To understand how climate affects trees and forest distributions, we need to know how trees regulate liquid flow and how the xylem and phloem tissues interact.
The project will consist of a multiscale experimental investigation of the changing geometry of the cellular structure and documentation of the liquid flow in these complex tissues, i.e. phloem and xylem. Advanced high resolution imaging techniques such as micro PIV, neutron tomography and synchroton X-ray nano/micro-tomography will be used. Advanced analysis methods include non-affine registration and computer microfluidics dynamics.