Studying microdroplet jetting using simulations
Karun Datadien defends his PhD thesis at the Department of Applied Physics and Science Education on January 31st.
For his PhD research, Karun Datadien explored an approach to simulate microdroplet jetting, as seen in inkjet printing, based on the Lattice Boltzmann Method. These simulations provided insight as to how the ink-air interface interacts with the micrometer-scale nozzles of an inkjet printer, which is otherwise difficult to observe in real experiments.
Along with his collaborators at the Department of Applied Physics and Science Education, Karun Datadien noted that their simulation method works well in capturing these interactions in a physically accurate manner.
This allowed for the study of inkjet phenomena that are difficult or expensive to recreate experimentally, because they happen on such a small scale and at high rates of speed and frequencies. Datadien’s simulation method can be used to run detailed 3D scenarios efficiently on high-performance computers.
As a result, Datadien was able to model jetting with real-world ink and air parameters in an accurate manner. In the printing industry, it was observed that tiny particles in the nozzle sometimes disturb the printing process, leading to low quality prints. It is challenging to recreate this in experiments because the occurrence of such particles is relatively rare. Simulations offer a cost-effective and easier way to explore different disturbances and their effects on printing.
Test cases
Simulations were tested and validated using known solutions for various test cases, and excellent agreement was found.
A comparison with another validated (non-3D) simulation method also showed good agreement. By adding specific boundary conditions to the simulation, Datadien was able to mimic complete printing cycles, including unwanted printing issues caused by changes in the nozzle shape, the occurrence of particles, or other factors.
For example, Datadien discovered that specifically sized or positioned blockages in the printer nozzle caused printed droplets to deviate from their intended path. He measured these deviations for different scenarios. Beyond printing, Datadien’s model could be useful for studying other systems with high-density differences between two liquids, like dense emulsions.
Title of PhD thesis: Directional instabilities in microdroplet jetting: a numerical approach. Supervisors: Federico Toschi and Herman Wijshoff.