Arnaldo Rodriguez-Gonzalez
@aghostinthefigures.bsky.social
Dynamicist, writer, asker of questions. Assistant professor of teaching in the University at Buffalo. Ph.D. in theoretical & applied mechanics from Cornell, B.S. in mechanical engineering from UPR Mayagüez. 🇵🇷 He/him.
More fun with computational fluid mechanics:
Here's a 2-D simulation of a layer of air (red) below a layer of water (blue) in a closed container. As air is lighter, buoyant forces cause the interface to be unstable, leading to the complex flow shown here as the air eventually rises to the top.
Here's a 2-D simulation of a layer of air (red) below a layer of water (blue) in a closed container. As air is lighter, buoyant forces cause the interface to be unstable, leading to the complex flow shown here as the air eventually rises to the top.
May 7, 2025 at 2:10 PM
More fun with computational fluid mechanics:
Here's a 2-D simulation of a layer of air (red) below a layer of water (blue) in a closed container. As air is lighter, buoyant forces cause the interface to be unstable, leading to the complex flow shown here as the air eventually rises to the top.
Here's a 2-D simulation of a layer of air (red) below a layer of water (blue) in a closed container. As air is lighter, buoyant forces cause the interface to be unstable, leading to the complex flow shown here as the air eventually rises to the top.
More fun with CFD for my course; here's a simulation of air bubbles being generated in a container of water with a rapidly rotating cylinder inside of it.
As time goes by, the cylinder rotation begins to affect the flow in the whole tank, and droplets start to drift to the right!
As time goes by, the cylinder rotation begins to affect the flow in the whole tank, and droplets start to drift to the right!
April 22, 2025 at 2:40 PM
More fun with CFD for my course; here's a simulation of air bubbles being generated in a container of water with a rapidly rotating cylinder inside of it.
As time goes by, the cylinder rotation begins to affect the flow in the whole tank, and droplets start to drift to the right!
As time goes by, the cylinder rotation begins to affect the flow in the whole tank, and droplets start to drift to the right!
If you look at a front view of the airfoil however, you see a key behavior that only shows up in proper 3-D treatments of flow around an airfoil—vortices!
As the fluid near the airfoil flows past it, it becomes deflected downwards by a pair of counter-rotating vortices off its back end.
As the fluid near the airfoil flows past it, it becomes deflected downwards by a pair of counter-rotating vortices off its back end.
April 17, 2025 at 9:07 PM
If you look at a front view of the airfoil however, you see a key behavior that only shows up in proper 3-D treatments of flow around an airfoil—vortices!
As the fluid near the airfoil flows past it, it becomes deflected downwards by a pair of counter-rotating vortices off its back end.
As the fluid near the airfoil flows past it, it becomes deflected downwards by a pair of counter-rotating vortices off its back end.
It is sometimes claimed that fluid takes the same amount of time traveling across the airfoil via either its top or bottom face; a side view of the flow (and particles traveling through it) confirms this is clearly not the case.
April 17, 2025 at 9:07 PM
It is sometimes claimed that fluid takes the same amount of time traveling across the airfoil via either its top or bottom face; a side view of the flow (and particles traveling through it) confirms this is clearly not the case.
More fun with computational fluid dynamics; what does flow past an airfoil look like? #FluidDynamics
A thread:
A thread:
April 17, 2025 at 9:07 PM
More fun with computational fluid dynamics; what does flow past an airfoil look like? #FluidDynamics
A thread:
A thread:
A perk of teaching students how to use finite element/volume methods; making cool animations!
This is "vortex shedding" in 2-D flow past a cylinder; a pair of symmetric counter-rotating vortices develop in the back, which then destabilize to form a long, oscillatory, transient wake. #fluidmechanics
This is "vortex shedding" in 2-D flow past a cylinder; a pair of symmetric counter-rotating vortices develop in the back, which then destabilize to form a long, oscillatory, transient wake. #fluidmechanics
April 12, 2025 at 5:46 PM
A perk of teaching students how to use finite element/volume methods; making cool animations!
This is "vortex shedding" in 2-D flow past a cylinder; a pair of symmetric counter-rotating vortices develop in the back, which then destabilize to form a long, oscillatory, transient wake. #fluidmechanics
This is "vortex shedding" in 2-D flow past a cylinder; a pair of symmetric counter-rotating vortices develop in the back, which then destabilize to form a long, oscillatory, transient wake. #fluidmechanics
Getting back in the habit of making math/physics animations in my spare time. Here's an old favorite of mine; the formation of a homoclinic tangle!
I'm hoping to upload the code for a few of these on GitHub, once I feel it's polished enough for public viewing. Hopefully won't take too long!
I'm hoping to upload the code for a few of these on GitHub, once I feel it's polished enough for public viewing. Hopefully won't take too long!
February 23, 2025 at 4:34 PM
Getting back in the habit of making math/physics animations in my spare time. Here's an old favorite of mine; the formation of a homoclinic tangle!
I'm hoping to upload the code for a few of these on GitHub, once I feel it's polished enough for public viewing. Hopefully won't take too long!
I'm hoping to upload the code for a few of these on GitHub, once I feel it's polished enough for public viewing. Hopefully won't take too long!
My plan was to get students to each simulate an individual test case with random design parameters, compile all data points, and see how they compare to the empirical "surface". Here it is! (The surface is the empirical prediction, dots are data points.)
Matches quite well except when h/r >> 1!
Matches quite well except when h/r >> 1!
February 17, 2025 at 9:40 PM
My plan was to get students to each simulate an individual test case with random design parameters, compile all data points, and see how they compare to the empirical "surface". Here it is! (The surface is the empirical prediction, dots are data points.)
Matches quite well except when h/r >> 1!
Matches quite well except when h/r >> 1!
This flow, however, is irrotational—viscous friction is neglected. Due to this, it's impossible for the flow to satisfy the no-slip condition on the sphere's surface, and so the particles that get close to the sphere just slip right past it.
This is one of the key issues with irrotational flow!
This is one of the key issues with irrotational flow!
December 7, 2024 at 9:21 PM
This flow, however, is irrotational—viscous friction is neglected. Due to this, it's impossible for the flow to satisfy the no-slip condition on the sphere's surface, and so the particles that get close to the sphere just slip right past it.
This is one of the key issues with irrotational flow!
This is one of the key issues with irrotational flow!
What does flow past a sphere look like when viscous friction dominates versus when it's neglected? Take a look for yourself! #physics
The flow below is creeping flow, where frictional effects dominate. Particles that get close to the sphere slow down drastically due to the no-slip condition.
The flow below is creeping flow, where frictional effects dominate. Particles that get close to the sphere slow down drastically due to the no-slip condition.
December 7, 2024 at 9:21 PM
What does flow past a sphere look like when viscous friction dominates versus when it's neglected? Take a look for yourself! #physics
The flow below is creeping flow, where frictional effects dominate. Particles that get close to the sphere slow down drastically due to the no-slip condition.
The flow below is creeping flow, where frictional effects dominate. Particles that get close to the sphere slow down drastically due to the no-slip condition.