Transport of particles and organisms in stratified and viscoelastic fluids

In this thesis, we unveiled the impact of fluid stratification and viscoelasticity on the transport of microorganisms and microparticles. The thesis is divided into four chapters. Chapters 2 and 3 focus on the transport of the swimming sheet in density and viscosity stratified fluids. Chapter 4 is devoted to analyze the motion of anisotropic particles in density stratified fluids. Chapter 5 focuses on the effect of viscoelasticity on the motion of a suspension of spherical particles.