the second part of the question: 2. Information for a column packed with sand le
ID: 113459 • Letter: T
Question
the second part of the question:
2. Information for a column packed with sand
length of sand column: 50 cm
grain size distribution shown as Curve 1 in problem 1
inside diameter of (circular) column: 6 cm
head change from inlet to outlet: 30 cm
hydraulic conductivity: 0.01 cm/s
porosity: 0.29
tortuosity: 0.75
a) what is the specific discharge, linear velocity, and interstitial velocity?
b) what is the Reynold’s number, and is the flow turbulent or laminar?
c) what is the intrinsic permeability of the sand?
1. Grain size distributions are shown in the figure below for three different samples. Calculate the uniformity coefficient for Curve 1 and report how well sorted the deposit is. [10] Silt Sand Gravel 10 90 80 70 60 50 40 30 20 0001 0.002 006 0.01 0.020.1 02 082 1020 60 100 sieve opening size (mm)Explanation / Answer
1) Uniformity Coefficient (Cu)= D60/ D10 = 0.05/0.006 = 5/0.6 = 8.33
Here, D60 is the size at 60% and D10 is the size at 10%.
Since Cu is greater than 5 (i.e. it is 8.33), it is a well graded deposit.
2) According to Darcy's Law,
Specific Discharge q = Q/A = K (h1 - h2) = 0.01 * 30 = 0.3 cm
K is the hydraulic conductivity. h1- h2 is the hydraulic head
Interstitial velocity represents the speed of the progressing molecules in the direction of movement.
v= Ki/n
Here, v is the velocity
K- hydraulic conductivity
i - hydraulic gradient
n - porosity
v = [0.01 * (30/50)] / 0.29 = 0.02068
b) Reynold's Number denotes the ratio of inertial forces to viscous forces for known conditions of flow. It is a dimensionless number. The flow is turbulent for Reynold's number >4000 while it is laminar for Reynold's number <2000.
c) Intrinsic permeability is the measure of the ability of the sand to allow fluids to pass through the interstitial spaces of the porous sand
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.