Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in a horizontal tube of 4 mm inner diameter in three idealizations of the EVLA procedure: water with a bare fiber tip, water with a carbonized layer on the fiber tip, and blood. Without boiling, the convection patterns in water and blood are similar and Grashof numbers are high enough to guarantee buoyancy induced flow and axial mixing, while preserving some stratification. A carbonized layer at the fiber tip promotes boiling in water at moderate laser powers. Boiling bubbles in water rapidly detach from the tip, with or without a carbonized layer, and promote mixing and a locally homogeneous temperature field. At 15 W laser power and 4 mm/s pullback speed in blood, a gas bubble may be formed that sticks at the fiber tip, causing strong local heating and possibly fiber damage.

Additional Metadata
Keywords Blood, Boiling, Endovenous laser ablation of varicosities, Laser ablation, Moving heat source, Water
Persistent URL dx.doi.org/10.1016/j.ijheatmasstransfer.2017.05.068, hdl.handle.net/1765/100134
Journal International Journal of Heat and Mass Transfer
Citation
de Boer, A. (Amit), Oliveira, J.L.G. (Jorge L.G.), van der Geld, C.W.M. (Cees W.M.), Malskat, W.S.J, van den Bos, R.R, Nijsten, T.E.C, & van Gemert, M.J.C. (2017). Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins. International Journal of Heat and Mass Transfer, 113, 153–165. doi:10.1016/j.ijheatmasstransfer.2017.05.068