# 338-0955/01 – Vehicle Aerodynamics (AV)

 Gurantor department Department of Hydromechanics and Hydraulic Equipment Credits 10 Subject guarantor doc. Ing. Marian Bojko, Ph.D. Subject version guarantor doc. Ing. Marian Bojko, Ph.D. Study level postgraduate Requirement Choice-compulsory type B Year Semester winter + summer Study language Czech Year of introduction 2020/2021 Year of cancellation Intended for the faculties FS Intended for study types Doctoral
Instruction secured by
BOJ01 doc. Ing. Marian Bojko, Ph.D.
Extent of instruction for forms of study
Form of studyWay of compl.Extent
Full-time Examination 25+0
Part-time Examination 25+0

### Subject aims expressed by acquired skills and competences

Students will be able to describe the flow types and the formation of the boundary layer and will be able to express the aerodynamic resistance of the bodies. They will know the basics of turbulent flow. They will be able to define the flow problems around road and rail vehicles at lower and high speeds. Understand the importance of aerodynamic elements in the construction of road and rail vehicles. They will be able to describe the principles of measuring the aerodynamic properties of vehicles in the aerodynamic tunnel. Students will be able to define marginal conditions after completing the subject and to construct a mathematical model of flow around and inside the vehicle and possibly including natural convection and heat transfer of walls. Students will then be able to apply a defined mathematical model to any CAD model and solve the final volume method using ANSYS Fluent or CFX software. An important part of the work will be the assessment of the solution, the comparison with the available theories and experiments and the determination of solvability limits for the area of aerodynamics of vehicles.

### Teaching methods

Lectures
Individual consultations
Experimental work in labs
Other activities

### Summary

The course focuses on the possibilities of mathematical modeling of flow connected with the obstruction of bodies (road and rail vehicles). Furthermore, with the creation of computational networks for mathematical modeling of flow. Students will broaden their theoretical knowledge in the area of weight, torque and heat transfer in turbulent flow. For the solution of the partial differential equations system describing the physical nature of the flow, the Final Volume Method (LCM) will be used. The application of the method will be directed to solving the boundary layer at the wall of the obtuse body. Further into the area of the aerodynamic resistance of the bodies. Subsequently to the area of complex aerodynamics of vehicles and therefore investigation of the flow in and around the vehicles connected with single-phase flow, flow of gaseous admixtures or multiphase flow with natural convection or heat transfer by wall. For practical applications, ANSYS Fluent or CFX software is used. The seminar work will cover the creation of a mathematical model and numerical solution of practical tasks that will be directed to the specific focus of doctoral dissertation.

### Compulsory literature:

HUCHO, Wolf-Heinrich. Aerodynamics of road vehicles: from fluid mechanics to vehicle engineering. 4th ed. Warrendale, PA: Society of Automotive Engineers, c1998. ISBN 978-0768000290. OBIDI, T. Theory and applications of aerodynamics for ground vehicles. xix, 267 pages. ISBN 978-076-8021-110. WILKES, J., O. Fluid mechanics for chemical engineers with Microfluidics and CFD. 2nd ed. Upper Saddle River: Prentice Hall Professional Technical Reference, c2006. Prentice Hall international series in the physical and chemical engineering sciences. ISBN 0-13-148212-2.

### Recommended literature:

KATZ, Joseph. Race car aerodynamics: designig for speed. 2nd rev. ed. Cambridge: Bentley Publishers, 2006, 307 s. ISBN 08-376-0142-8. INCROPERA, F. P., DEWITT, D. P., BERGMAN, T. L., LAVINE, A. S. Fundamentals of Heat and Mass Transfer. John Wiley & Sons, 2006, p. 997, ISBN 0-471-45728-0.

### Way of continuous check of knowledge in the course of semester

Oral examination.

### Other requirements

Semestral project on the defined topic and its presentation before examiner.

### Prerequisities

Subject has no prerequisities.

### Co-requisities

Subject has no co-requisities.

### Subject syllabus:

1. Definition of continuous environment, physical properties, diffusion and convective transmission, mass, momentum and energy transfer, basic equation of equilibrium (continuity equation, NS equation, energy equation), heat, heat output, heat transfer coefficient. 2. (DNS, LES, RANS), direct simulation (DNS), velocity simulation (LES, DES), time spanning method (RANS, classical k- model, RNG k- model, K-model, RSM model, Reynolds time span, turbulent quantities, bousinesqu hypothesis, Spalart-Allmaras turbulence model, turbulent flow input and output conditions. 3. Fundamentals of Numerical Modeling The Physical Principles of Mathematical Modeling, Reynolds Rules, Vector and Tensor Write of Equations, Numerical Methods of Solution of Flow, Numerical Solutions Navier - Stokes Equations and Continuity Equations by Basic Differential Methods, Integral Method, Finite Volume Methods, Finite Element Method, Spectral Method, finite volume method, finite volume method applied to a one-dimensional flow, solution of discretized equations, SIMPLE algorithm, SIMPLEC, multigrid methods, accuracy of differential schemes, network adaptation during simulation, modification of numerical parameters such as residual limitation, relaxation parameters, boundary conditions. 4. Limit layer of analytical solution of laminar and turbulent boundary layer (thickness of boundary layer, shear stress, friction coefficient) around horizontal plate, numerical solution of laminar and turbulent boundary layer (thickness of boundary layer, shear stress, friction coefficient) around the horizontal plate in ANSYS Fluent , wall functions, the importance of wall functions for speed and temperature profiles in modeling close to the wall, the criterion of dimensionless parameters y + when using wall functions, numerical solution of the boundary layer during the rolling of the bodywork of a road or rail vehicle (creation of a computing network, network refinement, definition of a mathematical model, wall functions, numerical solution and evaluation. 5. Aerodynamic resistance of vehicles, definition of resistance and buoyancy force, definition of friction and buoyancy coefficient, numerical solution of resistance and buoyancy force for windscreen wings in ANSYS Fluent, characteristics of reference values for evaluation of resistance force, buoyancy force, coefficient of friction and buoyancy coefficient, numerical resistive and buoyancy force solution for vehicle body wrapping in ANSYS Fluent. 6. Aerodynamic noise of vehicles Noise definition, noise quantification, types of aerodynamic noise, sources of noise, location of noise source and methods to eliminate sources of noise in the vehicle. 7. Experimental aerodynamics for terrestrial vehicles (wind tunnel) Characteristics of aerodynamic tunnel, measurements in aerodynamic tunnel. 8. Consumption, performance, stability, definition of power required to overcome air drag and roll, fuel consumption and measurement, tires, under-vehicle air flow, definition of pressure and its impact on stability and controllability. 9. Body shape of road vehicles, description of flow around the body of a road vehicle, definition of adherent and detached flow, Aerodynamic body requirements, methods of aerodynamic approach of passenger cars. 10. commercial vehicle aerodynamics, small commercial vehicles, buses, large commercial vehicles - legislative state, commercial aerodynamics tools for commercial vehicles. distribution of air resistance in the longitudinal axis of the vehicle and area of optimization cx, aerodynamics of trailers and semi-trailers and buses. 11. Aerodynamics of railway vehicles, resistances of railway vehicles, distribution of aerodynamic resistance on vehicles in the combination, influence of the shape of loco and railway wagons on their aerodynamic resistance, the influence of gearshift in tunnels, aerodynamic resistance in the tunnel, aerodynamic resistance of high speed units 12. Other parts of vehicle aerodynamics, internal aerodynamics of vehicle engines and measurement of flow coefficients, pollution of bodywork and cabinets, influence of vehicle accessories on their aerodynamics, comfort and comfort of crew, cooling and air conditioning 13. Minimization of aerodynamic drag Cx for vehicles, aerodynamic phenomena in the passage of vehicles through the tunnel, pressure surges during passing of vehicles, influence of pressure waves on persons along the track.

### Conditions for subject completion

Full-time form (validity from: 2020/2021 Winter semester)
Min. number of pointsMax. počet pokusů
Examination Examination   3
Mandatory attendence participation:

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Conditions for subject completion and attendance at the exercises within ISP:

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### Occurrence in study plans

Academic yearProgrammeBranch/spec.Spec.ZaměřeníFormStudy language Tut. centreYearWSType of duty
2024/2025 (P1041D040006) Transport Systems P Czech Ostrava Choice-compulsory type B study plan
2024/2025 (P1041D040006) Transport Systems K Czech Ostrava Choice-compulsory type B study plan
2023/2024 (P1041D040006) Transport Systems K Czech Ostrava Choice-compulsory type B study plan
2023/2024 (P1041D040006) Transport Systems P Czech Ostrava Choice-compulsory type B study plan
2022/2023 (P1041D040006) Transport Systems K Czech Ostrava Choice-compulsory type B study plan
2022/2023 (P1041D040006) Transport Systems P Czech Ostrava Choice-compulsory type B study plan
2021/2022 (P1041D040006) Transport Systems P Czech Ostrava Choice-compulsory type B study plan
2021/2022 (P1041D040006) Transport Systems K Czech Ostrava Choice-compulsory type B study plan
2020/2021 (P1041D040006) Transport Systems P Czech Ostrava Choice-compulsory type B study plan
2020/2021 (P1041D040006) Transport Systems K Czech Ostrava Choice-compulsory type B study plan

### Occurrence in special blocks

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### Assessment of instruction

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