The Particle Finite Element Method (PFEM) is a powerful numerical framework for simulating multiphase flows, particularly those involving free surfaces and complex fluid-structure interactions. By combining Lagrangian particle tracking with finite element discretization, PFEM is well-suited for accurately modeling bubble-laden flows. In this study, we evaluate the accuracy of PFEM in predicting the behavior of bubbles suspended in a Newtonian fluid under simple shear, validated against experimental data [1]. Bubble deformation is captured through adaptive mesh refinement near the interface [2], while computational efficiency is improved by modeling only the bubble interface and omitting internal flow dynamics. Incompressibility is enforced using a Lagrange multiplier, and the internal pressure follows the ideal gas law. Our results highlight PFEM’s capability in accurately capturing multiphase interactions, making it a valuable tool for studying bubbly suspensions in industrial and geophysical applications [3]. At low capillary numbers (Ca), surface tension dominates over viscous forces, causing bubbles to maintain a nearly spherical shape. In this regime, bubbles act as rigid obstacles that obstruct the flow, increasing the suspension's effective viscosity. As Ca increases, viscous forces become more significant compared to surface tension, allowing bubbles to deform and elongate. This deformation reduces their resistance to flow, progressively lowering the suspension’s effective viscosity.