LECTURE NOTES 
                          On 
               FLUID MECHANICS 
        
                                                 
                                                 
                                                 
                                                 
                                                 
                                                                                                                                                              PREPARED BY:- 
                                         Dr. Subasini Jena 
                                        Lecturer in Chemical Engg. 
                                                                                                                                                        UGIE, Rourkela 
                  
                 Definition of Fluid: 
                            A fluid is a substance which deforms continuously or flows when subjected to 
                             external shearing forces.  
                            A fluid is a substance which deforms continuously under the action of a shear 
                             stress. 
                            Both liquids and gases are termed as fluids. 
                              
                       Fluid flows – Shear stress ( yes) 
                         When the fluid is in flow condition so at that time the shear stress will be present and 
                         when the fluid is in rest condition at that time there is any shear stress will be present. 
                       Fluid flows – Shear stress ( No) 
                         If the fluid is at rest there is no any shearing force is acting on it, all force is must be 
                         perpendicular to the plane which they are acting. 
                 When the fluid is motion, shear stresses are developed due to the particles in the fluid moving 
                 relative to another. 
                 Example: – Fluid flowing in a pipe line for a fluid flowing in a pipe, fluid velocity will be 
                 zero at the pipe wall. Velocity will increase while moving towards the centre of the pipe. 
                               Fluid velocity will be zero at the pipe wall 
                  
                                                                                  Velocity maximum at centre of pipe 
                  
                  
                                              Fluid Velocity will be zero at the pipe wall 
                  
                 So, the shear force is at normally present because of adjacent layer of the fluid 
                 move with different velocities compared to each other.  
                  
                    Characteristics of Fluids (Liquid or Gas): 
                         1.  It has no definite shape of its own, but conforms to the shape of the containing vessel. 
                         2.   Even a small amount of shear force exerted on a fluid will cause it to undergo a 
                             deformation which continues as long as the force continues to be applied. 
                         3.  It is note to that a solid suffers strain when subjected to shear forces whereas a fluid 
                             suffers rate of strain i.e. it flows under similar circumstances. 
                              
                              
                              
                                                                    FLUID MECHANICS 
                              
                             Statics                                                                             Dynamics 
                      (Fluid at rest)                                                           (Fluid in motion, where pressure 
                                                                                                      forces are considered) 
                              
                                                      
                                                                      Kinematics  
                                         (Fluid in motion, where pressure forces are not considered) 
                              
                              
                             Fluid Mechanics – Fluid mechanics is the branch of science which deals with the 
                             behaviour of fluids (gases or liquid).  
                              
                             Fluid mechanics consists of: -  
                             1.  Fluid Statics – The study of fluids at rest is called fluid statics. 
                             2.  Fluid Dynamics – The study of fluids in motion where pressure forces is 
                                  considered is called fluid dynamics. 
                             3.  Fluid Kinematics - The study of fluids in motion where pressure force is not 
                                  considered is called fluid kinematics. 
                                   
                     
                              
                 PROPERTIES OF FLUIDS 
                             1.  Density or Mass density – Density of fluid is defined as the ratio of mass of 
                                 fluid to its volume. 
                                    It is denoted by symbol ρ 
                                    The unit of mass density or density is kg/m3 
                                    The value of density of water is 1gm/cm3 or 1000 kg/m3 
                                  
                                 Mathematically 
                                                                              
                                                                               
                             2.  Specific Volume – specific volume of a fluid is defined as the ratio of volume 
                                 of fluid to mass of fluid. 
                                  
                                    The unit of specific volume is m3/ kg 
                                  
                                 Mathematically 
                                                                                     
                                                                                           
                                                                                    
                 Specific volume is the reciprocal of mass density. It is commonly applied for gases. 
                             3.  Specific Weight or Weight density - Specific weight or weight density of 
                                 fluid is defined as the ratio of weight of fluid to its volume. 
                                           
                             Mathematically