a) Undistorted models:-

• Those models which are geometrically similar to their prototype or in other words if the scale ratio for linear dimensions of model and its prototype is same the model is called as undistorted model
• The behaviour of the prototype can be easily predicted from the result of undistorted model

b) Disorted models:-

• If model is not geometrically similar to the prototype then such model is said to be distorted model

• For distorted models different scale ratios for the linera dimensions are adopted

Some advantages of distorted models:-

1) The vertical dimensions of the model can be measured accurately

2) The cost of model can be reduced

3) Turbulent flow in the model can be maintained