A vibrational collisional model based on the database of the University of Bari is used to investigate nonequilibrium phenomena in nitrogen nozzle flows. For the cases studied, the vibrational distribution in the divergent section appeared to significantly deviate from a Boltzmann distribution. Multiquanta Vibration-Translation processes are shown to have a major influence on the recombination of the flow and on the shape of the vibrational distribution along the nozzle axis. Based on these results, a reduced model is derived with n groups of vibrational levels with their own internal temperatures to model the shape of the vibrational distribution. In this model, energy and chemistry source terms are calculated self-consistently from the rate coefficients of the vibrational database. For the studied nozzle flows, a good agreement is observed between the results of the vibrational collisional model with 68 levels and those of the reduced model with only 3 groups of levels.

Consistent multi-internal-temperatures models for nonequilibrium nozzle flows

Vibrational relaxation rates from Schwartz–Slawsky–Herzfeld theory and the forced-harmonic oscillator model are used to study the flow of nitrogen in the stagnation region of a blunt body. The mass conservation equations are coupled to the momentum and total energy equations, and solved using an implicit finite-volume computational fluid dynamics method. The effects of single- and multiple-quantum vibration–translation transitions and vibration–vibration transitions are studied. Also, the effect of the mass diffusion of the excited oscillators across the shock layer is investigated. It is found that highly non-Boltzmann vibrational distributions are present in the flow field, and that the forced-harmonic oscillator model predicts that dissociation occurs from the low vibrational levels only.

Detailed simulation of nitrogen dissociation in stagnation regions

Numerical simulations are presented of a steady-state, hypersonic e ow over a two-dimensional cylinder of 1 m radius under conditions where the relaxation of the vibrational modes is signie cant. A Mach 6.5 nitrogen e ow was simulated atfreestream pressuresof50, 250, and500 Pa, witha freestream translational temperatureof300K.Two differentfreestream vibrationaltemperatures,300K (causing vibrationalheating )and4000K(causing vibrational cooling)were considered to study the effects on the e owe eld. An upwind-difference numerical scheme was used to solve the inviscid Euler equations coupled to the vibrational kinetic models of diatomic nitrogen, assumed as an anharmonic oscillator of 40 quantum levels using two sets of reaction rates. Comparison with previously reported computations showed a maximum variation of 10% in translational and e rst-level vibrational temperature along thesurfaceduetodifferencesinnumericalschemesandgriddensities;variationcausedbythetwodifferentreaction rate sets was less than 2%. The vibrational cooling case showed a 10% higher shock-standoff distance than the vibrational heating case. The population distribution for the cooling case was non-Boltzmann due to nonresonant energy exchangesin the postshock region, greaterin theshoulder region than in thestagnation region. An increase in freestream pressure for the cooling case increased the shock-standoff distance and non-Boltzmann behavior in the postshock region and near the surface. There was, however, a larger equilibrium region in between, in the stagnation region.

Computational Study of Vibrationally Relaxing Gas past Blunt Body in Hypersonic Flows

An MPI-CUDA approach for hypersonic flows with detailed state-to-state air kinetics using a GPU cluster

Models validation and code profiling in state-to-state simulations of shock heated air flows

The results of a numerical study aimed to verify the accuracy of the thermodynamic models based on the Boltzmann distribution in the hypersonic regime and to detect discrepancies, if any, with the analysis based on the more rigorous method of vibrational kinetics are presented and discussed. The test case considered in the study is the steady, two-dimensional, chemically inert, inviscid e ow of diatomic nitrogen past an ine nite cylinder in a uniform stream at M = 6.5. The vibrational relaxation has been calculated from the standard vibrational energy rate equation, assuming a harmonic ‐ oscillator behavior of N 2, and from a set of vibrational master equations that account for the e rst 10 vibrational energy levels of the N2 molecule, assumed as an anharmonic oscillator. The e ow patterns produced by the two calculation methods are thoroughly discussed and the critical ine uence of the vibrational relaxation time, associated with the harmonic ‐ oscillator models, in determining agreement or disagreement with the results from the vibrational kinetics method is evidenced.

Vibrationally Relaxing Flow of N 2 past an Iné nite Cylinder

Vibrationally relaxing flow of N2 past an infinite cylinder according to state-to-state vibrational kinetics and to the harmonic-oscillator model

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

D. Giordano

Author Tools

Chat about Author

Papers

Vibrationally Relaxing Flow of N 2 past an Iné nite Cylinder

Vibrationally relaxing flow of N2 past an infinite cylinder according to state-to-state vibrational kinetics and to the harmonic-oscillator model