Any field that includes studies of Fluid Mechanics or Concentration flow /movement /Populations will have a high degree of mathematics...considering these topics are all applied mathematics. These fields include, Molecular dynamics, water, population dynamics(ecological ,predator prey dynamics or cell populations), atmospheric modelling, geophysics,Solid modelling.
Spiking Neurons/neural networks/brain modelling apply a high degree of ODE/PDE also
There are also application of combinatorics to Genome Studies(including Grapht theory), Molecular Modelling also uses COmputational Geometry.
Anytime you include properties such as spatial coordinates
,movement, how many, permutation/arrangement you will apply quite abit of math. The complexity in math depends on the complexity in the topic.