Pimentel's blog

Go to the first part:  On the irrationality (not irrotationality) of some "experts" (Part 1) During the re-election campaign last April-May, I made public a series of two articles, titled "On innovation and other hoaxes" *, available in both Spanish and Catalan on my alternative blog,  Blog de Pimentel  (with an accent on the last 'e'). In these articles, I exposed the arbitrary actions committed by both the former rector and the PhD doctoral coordinator, those who tried to cover up responsibilities and protect everyone involved in this situation.  The political dimension of the conflict became evident when the doctoral coordinator was surprisingly involved as a campaign coordinator for the former rector, while the former Doctoral School director, who held the position at the time of the events, was also a member of that electoral team . The first article aimed to detail the situation and the violations of internal university legislation. Following its publi...

VERSIÓN EN ESPAÑOL :  Sobre la irracionalidad de algunos “expertos” (Parte 1) 📝  Why I Once Called Myself a “Dummy” — And Why It Worked Two years ago, I wrote a blog post titled " Fluid dynamics for dummies, like me: on potential flows ". The title had a double intention: on one hand, I was being honest. The "experts" might consider that I am just beginning my journey in the vast universe of aerodynamics and fluid dynamics, starting with the simplest case — incompressible flow. On the other hand, I wanted to poke a bit at a certain type of expert who dismisses Potential Flow Theory (PFT) as outdated or irrelevant. Some people didn’t appreciate the joke. Fig. 1 Potential flow solution for a parabolic parachute canopy (for added masses calculation; Pimentel, 2016). Note the clown face in the upper figure. One well‑known “potentialist” on LinkedIn took the title as a personal attack. Instead of reading and understand the intention of the article, he blocked me and cr...

Go to the first part:  An 'inviscid' boundary layer! Is this a bug?! (Part 1) Approximately a year ago, I published the initial parts of a series detailing a significant visualization anomaly encountered within the Results module of ANSYS Workbench. I recently tested the newest ANSYS Student version (2025 R2) with the same 2D test case, and unfortunately, the issue persists despite having been reported in the official forum: a modeled boundary layer (BL) appears in the visualization for an inviscid flow simulation (over both an airfoil and a 3D wing; see Fig. 1). It is crucial to emphasize that this visual error does not appear in the ANSYS Fluent solver module. Since the solver correctly recognizes the inviscid condition (μ=0), it does not impose a no-slip condition at the wall, and thus, no BL is formed in the flow solution itself.  As those with a fundamental knowledge of fluid dynamics understand this is not a personal interpretation error, I believe this bug is primarily...

Around two years ago, I launched this blog with the initial goal of demystifying my doctoral research, translating complex concepts and terminology into simple language accessible to a general audience. While many early articles focused on straightforward explanations (mostly in Spanish), the content naturally evolved to address deeper technical inquiries from engaged readers. This entire process has been a valuable exercise for organizing my thoughts and sharpening my scientific communication skills. Since beginning this project, I have successfully authored and published one paper in a Q1 journal [1] and co-authored a second paper available on ArXiv [2] as a preprint. Furthermore, I utilized this knowledge to successfully prepare and file by myself the corresponding patent application [3], saving hundred of dollars in an attorney. My research is fundamentally open. I offer my findings for review and use by the community, having moved past the need to convince any particular audience....

 This is a second version of the original article:  Can a brick 'fly' (glide)? This time, Google's AI Gemini (Flash v2.5) enhanced (or not...) this article by simply adding "Improve this:" to each original paragraph. This was done as an exercise to provide an alternative explanation and formatting while maintaining the original ideas. No major changes have been made to the AI-generated text, and the additional explanations (marked with asterisks in the original article) have been removed. Redefining Aerodynamics: Beyond the Smooth Surface Yes, it can—but perhaps not in the way most people understand. The common perception of "aerodynamics" often fixates on curvatures, rounded leading edges, smooth surfaces, and sharp trailing edges . These features, while visually appealing and often associated with modern design, are largely just cosmetic embellishments when we consider the fundamental meaning of the term. Etymologically, "aerodynamics" si...

Go to the first part:  On innovation and other hoaxes: a true story at university (Part 1) Most real aerodynamicists, even computationalists, know the typical pressure coefficient (cp) distribution for an airfoil (with positive AoA) in the pre-stall region,  cp tends to increase from the suction side (top) towards the leading edge (LE), typically with a negative peak value. On the other hand, at the frontal stagnation point, such a value must be equal to 1 (for the incompressible case), which no longer coincides with the geometric frontal point of the airfoil, since it is naturally shifted backwards due to its inclination. Obviously, a zero value of cp must be located in such a curved region, i.e. close to the geometric frontal point (see Fig. 1). But what happens if instead of an airfoil we use an "infinitely thin" flat plate? Yes, in the limit of thickness equal to zero, cp must be equal to the difference between the upper and lower side cp's , which have a different...