Working on a methodology different from advisor's expertise. How to proceed? I am pursuing PhD in materials engineering. My advisor is an expert in molecular dynamics (MD) simulations and density functional theory. She works with nanomaterials and batteries. However, for my research, she wants me to work with finite element analysis (FEA) and smoothed particle hydrodynamics as I will work in simulating additive manufacturing process. She doesn't have knowledge or past experience on these methodologies.
I tried to argue about using MD for my research as there are groups who use the method in similar research work as mine. But she says that those groups are not doing good work and MD can't be applicable for my research. She says, just because they can publish papers doesn't mean that they are doing good work.
Now, I am worried that how I will get proper guidance if she doesn't know about my research methods. How should I proceed? I don't have a co-supervisor.
A PhD is a learning experience, so don't worry about stepping out into a new domain. It's also not uncommon for the supervisor to not be familiar with all the research methods you use, since the field has changed a lot since they were engaged in active research.
I understand that this seems daunting, but try to find a support ecosystem where you can get practical tips on day-to-day technical support. There are good resources available online, and very often you are expected to find those out by yourself.
If the supervisor is otherwise good and has a good track record, I suggest you continue with her and give it a shot with an open mind.
Finally, having dabbled in all the areas/tools you mentioned, I have to say I strongly agree with your supervisor, especially from an applied research perspective. In the long run, the effort will probably be well worth it.