The enclosed thesis details an investigation into the simulation of microcombustors with thermally orthotropic walls, using Eilmer4. The thesis details the motivational context for the work completed, then utilises this foundation to define the scope and aims of the project; the development of functional microcombustors simulations in Eilmer4. An initial review of relevant literature, predominantly relating to previous works in simulating microcombustion and heat recirculation. From the review of literature, a series of required simulation features allowing microcombustors with thermally orthotropic walls to be simulated in Eilmer4. These features and the varying degrees of implementation were documented and used to direct efforts towards a functioning microcombustor model with thermally orthotropic walls; the numerical approach required to allow various solid-fluid interfaces with the previously developed anisotropic sold module. Pending the implementation of the numerical schemes proposed two sets of simulations were completed. The first relating to simulating an insulated microcombustor for both the isotropic and thermally orthotropic considerations; serving to confirm the model. The second set of simulations considered the modelling of microcombustors with a high degree of thermal orthotropy, and the flame response in the presence of convective heat loss on the external combustor surface; with short term simulations achieving flame stability for the prescribed simulation conditions.