Engineering Questions with Answers - Multiple Choice Questions

# Computational Fluid Dynamics – Boundary Conditions

1 - Question

Which among these is used to specify a particular problem which we consider for solving in CFD?
a) Boundary conditions
b) Governing equations
c) Governing laws
d) Solution method
Explanation: Boundary conditions can define a particular problem. When the same governing equations are used to solve different problems, boundary conditions are the one which makes the problem unique.

2 - Question

What are the two major types of boundary conditions?
a) Wall and symmetry
b) Inlet and outlet
c) Dirichlet and Neumann
d) Initial and physical
Explanation: Dirichlet and Neumann boundary conditions are the two boundary conditions. They are used to define the conditions in the physical boundary of a problem.

3 - Question

Which of these best define the Dirichlet boundary conditions for the property Φ at a point ‘b’ in a boundary?
a) ∂3Φ∂3x
b) ∂2Φ∂2x
c) ∂Φ∂x
d) Φb
Explanation: Dirichlet boundary conditions are where the values of the properties are directly given. So, among the options given, Φb represents the Dirichlet boundary condition.

4 - Question

The boundary condition represented in the following diagram is ___________ a) Dirichlet
b) Periodic
c) Neumann
d) Axisymmetric

Explanation: In the diagram, the heat flux value is given. This kind of boundary condition where the flux of a property is given is called the Neumann boundary condition.

5 - Question

The Neumann and Dirichlet boundary conditions are _________ and _________ in mathematical terms.
a) value specified, flux specified
b) flux specified, value specified
d) value specified, time specified
Explanation: In mathematical terms, Neumann Boundary conditions are called flux specified and Dirichlet boundary conditions are called value specified boundary conditions. These names are based on their characteristics.

6 - Question

In Dirichlet boundary conditions, the flux values _________
a) can be calculated
b) are unknowns
c) are known
d) are 0
Explanation: In Dirichlet boundary conditions, the value of the flow property will be given. By using this, the flux values can be created. They are not unknowns.

7 - Question

Initial conditions are used for __________ problems.
a) time-dependent problems
b) boundary value problems
c) control volume problems
d) finite difference problems
Explanation: For time-dependent problems, initial conditions are used to specify the conditions at t=0. This will be helpful to find the solutions at the time points.

8 - Question

Which among these is a combination of value specified and flux specified boundary conditions?
a) Dirichlet
b) Mixed
c) Neumann
d) Symmetry
Explanation: Type 3 boundary conditions are the mixed boundary conditions. Mixed boundary condition combines Neumann and Dirichlet boundary conditions.

9 - Question

Which of these is not a combination of Neumann and Dirichlet Boundary conditions?
a) Cauchy boundary conditions
b) Wall boundary conditions
c) Mixed boundary conditions
d) Robin boundary conditions
Explanation: Wall boundary conditions are the boundary conditions specified at walls. The other types (Cauchy, mixed and Robin boundary conditions) are different combinations of Dirichlet and Neumann Boundary conditions.

10 - Question

Which is not a type of boundary conditions in CFD?
a) Cyclic boundary conditions
b) Symmetry boundary conditions
c) Wall boundary conditions
d) Nodal boundary conditions