Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
19 Cards in this Set
- Front
- Back
|
Dimensional Analysis |
• A method for reducing the number and complexity of experimental variables which affect a given physical phenomenon • Involves the analysis of dimensions of quantities or variables • Basis: An equation expressing a physical relationship between variables must be dimensionally homogenous. • When combined with experimental methods, results in accurate prediction equations |
|
|
Dimension |
a category that represents a physical quantity Primary Dimensions • Length (L)* • Mass (M)* • Time (T)* • Temperature (θ) Derived Quantities • Velocity (LT-1 ) • Force (MLT-2 ) • Pressure (ML-1T-2 ) |
|
|
Unit |
a measure of a specific dimension Primary • Length (m) • Mass (kg) • Time (s) • Temperature (K) Derived • Velocity (m/s) • Force (N or kg∙m∙s-2 ) • Pressure (N/m-2 or kg∙m-1s-2 m-2 ) |
|
|
Boundary Geometry |
• Length (L) • Area (L2) • Volume (L3) |
|
|
Fluid Property |
• Density (ML-3) • Specific Weight (ML-2T-2) • Dynamic Viscosity (ML-1T-1) • Compressibility (ML-1T-2) • Surface Tension (ML-2) |
|
|
Buckingham Pi Theorem |
- Edgar Buckingham |
|
|
Common Dimensionless Ratios Reynolds Number Froude Number Euler Number Weber Number Mach Number |
Osborne Reynolds William Froude Leonhard Euler Moritz Weber Ernst Mach
|
|
|
Reynolds Number |
Inertial forces/ viscous forces
Any physical phenomenon that involves real fluid flow (with viscous effects). |
|
|
Froude Number |
Inertial forces/ gravity forces Free surface flow |
|
|
Euler Number |
Pressure forces/ inertial forces Aerodynamics and hydrodynamics |
|
|
Weber Number |
Inertial forces/ surface tension Free-surface flow where surface tension may not be neglected, multiphase flows |
|
|
Mach Number |
Inertial forces/ compressive forces Compressible flow |
|
|
Similitude |
The theory and art of predicting prototype (actual) performance based on model observations. |
|
|
Mathematical Models |
Solves analytical equations using numerical methods (FDM, FEM, FVM) with known boundary conditions |
|
|
Physical Models |
Includes creation of a miniature system (model), exposing it to different flow scenarios, measuring flow parameters, and relating the observed results into the actual system (prototype) |
|
|
Geometric Similarity |
A model and prototype are geometrically similar if and only if all body dimensions in all three coordinates have the same linear- scale ratio |
|
|
Kinematic Similarity |
The motions of two systems are kinematically similar if homologous particles lie at homologous points at homologous times |
|
|
Dynamic Similarity |
A model and a prototype are said to be dynamically similar if all the forces that act on corresponding masses are in the same ratio throughout the entire flow field |
|
|
Limitations of Physical Models |
Most of the time, only the governing criterion/law is being satisfied by the model given a certain length ratio Most fluid flow models are designed according to the dominant force influencing the phenomena being investigated Interpretation of model results requires a basic knowledge of fluid mechanics and a lot of experience since the similitude law is seldom satisfied. |
