What causes 'round off' error in numerical solution?

Finite grid points

Solving nonlinear equation

Incoherent boundary conditions

Rounding number to a significant figure

Correct Answer : Rounding number to a significant figure

Explanation : Numerical solutions are obtained using the computers which often rounds off every number to a certain significant digit. Each of these rounding off results in small errors. If we decrease the truncation errors, the round – off error increases and these errors is a function of step size ?x.

Recently Updated in Aerodynamics Questions

What is the region of influence?

Area outside right running wave

Area outside the left running wave

Area within the upstream characteristics

Area within the downstream characteristics

Correct Answer : Option (D) : Area within the downstream characteristics

Explanation : For a point A which is present in a flow field with incoming steady supersonic flow, there will be two characteristic lines passing through them. The area formed between these two characteristics in the downstream region is known as region of influence.

For a point in the supersonic flow lying at the intersection of the characteristics, its flow field properties depend on change in which of these regions?

Region of influence

Domain of dependence

Region outside the characteristics

Intersection points of the characteristics

Correct Answer : Option (B) : Domain of dependence

Explaination : If a point P lies at the intersection of the left and right running waves, the flow field properties at point P is dependent on the flow field information in the region upstream i.e. domain of dependence.

On which of these points does the properties of flow field at point A depend?

Point B

Point C

Point D

Point P

Correct Answer : Option (D) : Point P

Explaination : Point P lies at the intersection of the two characteristic lines. Point A lies in the region of influence thus its flow properties depend on the properties generated due to disturbances at point P which is the intersection point.