Aria Alimi - Academia.edu (original) (raw)
Uploads
Papers by Aria Alimi
Fluids
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generat... more Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the laminar boundary-layer separation. However, the present results indicate that using the same blowing amplitude, harmonic VGJs were more effective and efficient at reducing the separated region than the steady VGJs considering the fact that the harmonic VGJs use less momentum than the steady case. For steady VGJs, longitudinal structures forming immediately downstream of the injection location led to the formation of hairpin-type vortices, causing an earlier transition to turbulence. Symmetric hairpin vortices were shown to develop downstream of the forcing location for the harmonic VGJs, as well. However, the increased control effectiveness for harmonic VGJs’ flow control strategy is attributed to the fact that the shear-layer instability mechanism was...
PAMM
Blood flow simulation of complex arterial networks in three-dimensions generally involves assigni... more Blood flow simulation of complex arterial networks in three-dimensions generally involves assigning multiple inlets and outlets. This work investigates different kinds of boundary condition assigned on inlets and outlets in the Circle of Willis. These boundary conditions will be adopted in a way that a realistic velocity profile and pressure in the main brain arteries are achieved. The result of this work will be used for Fluid-structure interaction simulations. As the force applied on the artery wall depends on the blood pressure, the goal is to achieve a pressure boundary condition based on the in-vivo flow rates in each artery.
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generat... more Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the laminar boundary-layer separation. However, the present results indicate that using the same blowing amplitude, harmonic VGJs were more effective and efficient in reducing the separated region than the steady VGJs considering the fact that the harmonic VGJs use less momentum than the steady case. For steady VGJs, longitudinal structures formed immediately downstream of injection location led to formation of hairpin-type vortices causing an earlier transition to turbulence. Symmetric hairpin vortices were shown to develop downstream of the forcing location for the harmonic VGJs as well. However, the increased control effectiveness for harmonic VGJs flow control strategy is attributed to the fact that shear-layer instability mechanism was exploited. As a...
PAMM
This work involves studying the role of the Brain Blood Barriers (BBB) on damping the stress appl... more This work involves studying the role of the Brain Blood Barriers (BBB) on damping the stress applied on brain tissue through blood pressure that is the main cause of brain aneurysm. The numerical simulations are focused on the geometry of the Anterior Communicating Artery (ACoA) because there is a 30% higher probability for a brain aneurysm in this location. A linear elastic model is used to model the structure part including BBB and brain tissue. Regarding the fluid properties, blood is assumed to behave as a Newtonian fluid. The stress and deformation of the brain tissue is analyzed.
Fluids
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generat... more Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the laminar boundary-layer separation. However, the present results indicate that using the same blowing amplitude, harmonic VGJs were more effective and efficient at reducing the separated region than the steady VGJs considering the fact that the harmonic VGJs use less momentum than the steady case. For steady VGJs, longitudinal structures forming immediately downstream of the injection location led to the formation of hairpin-type vortices, causing an earlier transition to turbulence. Symmetric hairpin vortices were shown to develop downstream of the forcing location for the harmonic VGJs, as well. However, the increased control effectiveness for harmonic VGJs’ flow control strategy is attributed to the fact that the shear-layer instability mechanism was...
PAMM
Blood flow simulation of complex arterial networks in three-dimensions generally involves assigni... more Blood flow simulation of complex arterial networks in three-dimensions generally involves assigning multiple inlets and outlets. This work investigates different kinds of boundary condition assigned on inlets and outlets in the Circle of Willis. These boundary conditions will be adopted in a way that a realistic velocity profile and pressure in the main brain arteries are achieved. The result of this work will be used for Fluid-structure interaction simulations. As the force applied on the artery wall depends on the blood pressure, the goal is to achieve a pressure boundary condition based on the in-vivo flow rates in each artery.
Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generat... more Active flow control of canonical laminar separation bubbles by steady and harmonic vortex generator jets (VGJs) was investigated using direct numerical simulations. Both control strategies were found to be effective in controlling the laminar boundary-layer separation. However, the present results indicate that using the same blowing amplitude, harmonic VGJs were more effective and efficient in reducing the separated region than the steady VGJs considering the fact that the harmonic VGJs use less momentum than the steady case. For steady VGJs, longitudinal structures formed immediately downstream of injection location led to formation of hairpin-type vortices causing an earlier transition to turbulence. Symmetric hairpin vortices were shown to develop downstream of the forcing location for the harmonic VGJs as well. However, the increased control effectiveness for harmonic VGJs flow control strategy is attributed to the fact that shear-layer instability mechanism was exploited. As a...
PAMM
This work involves studying the role of the Brain Blood Barriers (BBB) on damping the stress appl... more This work involves studying the role of the Brain Blood Barriers (BBB) on damping the stress applied on brain tissue through blood pressure that is the main cause of brain aneurysm. The numerical simulations are focused on the geometry of the Anterior Communicating Artery (ACoA) because there is a 30% higher probability for a brain aneurysm in this location. A linear elastic model is used to model the structure part including BBB and brain tissue. Regarding the fluid properties, blood is assumed to behave as a Newtonian fluid. The stress and deformation of the brain tissue is analyzed.