Lecture 1.2

Question 1

Sedimentation

Answer 1

The process by which the separation of phases takes place under the action of gravity(gravity forces) and the particles are deposited on the bottom of a liquid volume and form a precipitation (sediment).

Question 2

Heterogenous systems

Answer 2

Composed of two or more phases and contain structural elements

Question 3

Rheology

Answer 3

The branch of mechanics that studies the properties of gases and liquids to flow and the properties of solid bodies

Question 4

Newtonian fluids

Answer 4

-Fluids that obey Newton’s law
-They are water, true solutions, low molecular weight organic compounds
-Dynamic viscosity coefficient depends on the type of liquid and the presence of impurities in it, and for a given liquid on the temperature, but does not depend on the velocity gradient

Question 5

Non-Newtonian fluids

Answer 5

-Fluids that do not obey Newton’s law of viscosity
-Viscosity can change when under force to either more liquid or more solid
-Many salt solutions and molten polymers are non-Newtonian fluids, as well as blood, toothpaste and shampoo, etc.

Question 6

Viscosity of solutions and suspensions

Answer 6

Changes if liquid or solid substances are dissolved or dispersed in it

Question 7

Einstein’s equation importance

Answer 7

The viscosity of a suspension with uniformly distributed particles can be determined by einstein’s equation

Question 8

Reasons for Non-Newtonian character

Answer 8

-Changes in the orientation
-Aggregation and disaggregation of the particles
-Deformation caused by the velocity gradient

Question 9

Dilatant movement

Answer 9

-The increase in viscosity with an increase in the velocity gradient
-This behaviour is observed because the system crystalises under stress and behaves more like a solid

Question 10

Bingham fluid/plastic

Answer 10

-Visco plastic material that behaves as a rigid body at low stresses but flows as a viscous fluid at high stress
-Mimic solids under low-shear stresses

Question 11

The effect of hematocrit on blood viscosity

Answer 11

-Increasing red cell hematocrit increases relative velocity
-The increase is non linear, increased hematocrit causes a disproportionate increase in relative viscosity.
-At a normal hematocrit of 40%, the relative viscosity of blood is about 4%