Numerical Analysis of Stem Wave Control Effect of a Curved Slit Caisson Breakwater

Curved slit caisson has been the preferred structural type of breakwater in South Korea, and effective control of stem waves is a crucial design factor significantly affecting the performance of a curved slit caisson breakwater. Most of the past studies on stem waves heavily relied on wave drivers like the cubic Schrödinger Eq. due to the intrinsic difficulties in analyzing stem waves. However, considering the perturbation method evoked in the derivation of cubic Schrödinger Eq., the wave driver mentioned above could give erroneous results in the rough sea due to the higher-order waves that appeared in the wave field by resonance wave-wave interaction. In this rationale, in this study, the numerical simulation was implemented to verify the stem wave control effect of curved slit caisson using the ihFoam, toolbox having its roots on OpenFoam. It was shown that curved slit caisson breakwater effectively alleviates the scope and height of stem waves.

Dissociative Electron Attachment in C2H via Electronic Resonances

<div> <div> <div> <div> <p>Investigation of microwave-activated CH₄/H₂plasma used in chemical vapor deposition of diamond revealed the presence of electronically excited C₂^-(B²Σ_u⁺). Using high-level electronic structure methods, we investigate electronic structure of C₂H^- and suggest possible routes for formation of C₂^- in the ground (X²Σ_g⁺) and excited (B²Σ_u⁺) states via electronic resonances. To describe electronically meta-stable states, we employ the equation-of-motion coupled-cluster method augmented by the complex absorbing potential. The resonance wave-functions are analyzed using natural transition orbitals. We identified several resonances in C₂H^-, including the state that may lead to C₂^-(B²Σ_u⁺). </p><p> </p> <p></p><p> </p> <p> </p> <p> </p> </div> </div> </div> </div>

Dissociative Electron Attachment in C2H via Electronic Resonances

<div> <div> <div> <div> <p>Investigation of microwave-activated CH₄/H₂plasma used in chemical vapor deposition of diamond revealed the presence of electronically excited C₂^-(B²Σ_u⁺). Using high-level electronic structure methods, we investigate electronic structure of C₂H^- and suggest possible routes for formation of C₂^- in the ground (X²Σ_g⁺) and excited (B²Σ_u⁺) states via electronic resonances. To describe electronically meta-stable states, we employ the equation-of-motion coupled-cluster method augmented by the complex absorbing potential. The resonance wave-functions are analyzed using natural transition orbitals. We identified several resonances in C₂H^-, including the state that may lead to C₂^-(B²Σ_u⁺). </p><p> </p> <p></p><p> </p> <p> </p> <p> </p> </div> </div> </div> </div>

Beautiful Neduvangiyam also known as Nagasuram

The purpose of this study is to understand one of the earliest known non-brass double-reed instrument called Nagasuram (Nadaswaram). Our ancestors while defining Tamil music grammar in parallel focused on sound engineering, which helped them to invent new musical instruments. Sangam era alone saw more than 30 percussion and wind instruments. Among them, few instruments like Veenai, Urumi and Nagasuram are worth mentioning since their design techniques were known only to a handful of families. Their performance really stands out due to their versatile and adaptable nature to all genres of music. Music instrument, like any other scientific invention goes through the same process of trial and error before getting standardized for general use. Instruments with strong adherence to scientific and acoustic principles gain prominence among the rest, as they undergo minimal structural changes. Nagasuram (Nadaswaram) is one such instrument, which was passed on to us for generations. This instrument readily complies with acoustic principles such as sound impedance, Helmholtz resonance, wave theory etc. to get the characteristic of a loudest non-brass wind instrument.

On the wave turbulence theory for stratified flows in the ocean

After the pioneering work of Garrett and Munk, the statistics of oceanic internal gravity waves has become a central subject of research in oceanography. The time evolution of the spectral energy of internal waves in the ocean can be described by a near-resonance wave turbulence equation, of quantum Boltzmann type. In this work, we provide the first rigorous mathematical study for the equation by showing the global existence and uniqueness of strong solutions.

Numerical modeling of fluid resonance in narrow gaps of fixed rectangular structures

A two-dimensional numerical model is developed to investigate the phenomenon of resonance in narrow gaps. Instead of using commonly used Volume of Fluid method to capture the free surface which is sometimes difficult to capture the geometric properties of the geometrically complicated interface, the free surface is traced by using Arbitrary Lagrangian–Eulerian method. The numerical model is based on the two-dimensional Reynolds-Averaged Navier–Stokes equations. The numerical model is validated against wave propagation in wave flume. Comparisons between the numerical results and available theoretical data show satisfactory agreements. Fluid resonance in narrow gaps of fixed rectangular structures are simulated. Numerical results show that resonance wave height and wave frequency for rectangle boxes with sphenoid corners is larger than for rectangle boxes.