Flow Through a Packed Bed
Fluid Mechanics · FE Reference Handbook section
Handbook notes for this section
Definitions and conditions exactly as the handbook states them.
- A porous, fixed bed of solid particles can be characterized by
- The Ergun equation can be used to estimate pressure loss through a packed bed under laminar and turbulent flow conditions.
- Submerged Orifice Operating under Steady-Flow Conditions:
- in which the product of Cc and Cv is defined as the coefficient of discharge of the orifice.
Core formulas for this FE topic
Definitions, applicability, units, assumptions and worked examples for each relation.
Worked exam-style examples
The four ways this section is written on the real exam — thoughts first, then equations, then substitution.
flow through a packed bed of granular filter media Given dynamic viscosity (mu) = 0.0006 Pa*s; bed porosity (epsilon) = 0.3100; superficial velocity (V) = 0.0360 m/s; gravity (g) = 9.7400 m/s^2; fluid density (rho) = 820.0 kg/m^3; particle diameter (D_p) = 0.0028 m; bed depth (L) = 1.2000 m, determine the head loss (h_f) in m.
Given
Find
head loss (h_f), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except h_f is given, so isolate h_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h_f stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0006 Pa*s, bed porosity (epsilon) = 0.3100, superficial velocity (V) = 0.0360 m/s, gravity (g) = 9.7400 m/s^2, fluid density (rho) = 820.0 kg/m^3, particle diameter (D_p) = 0.0028 m, bed depth (L) = 1.2000 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h_f = 0.9923 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1.9846 — kept a factor of two that cancels in the correct rearrangement.
- 0.4962 — dropped that same factor in the other direction.
- 1.0915 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed reactor with spherical particles Given dynamic viscosity (mu) = 0.0017 Pa*s; bed porosity (epsilon) = 0.3100; gravity (g) = 9.8300 m/s^2; fluid density (rho) = 1,030 kg/m^3; particle diameter (D_p) = 0.0068 m; bed depth (L) = 0.4000 m; head loss (h_f) = 3.3580 m, determine the superficial velocity (V) in m/s.
Given
Find
superficial velocity (V), in m/s
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that V stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0017 Pa*s, bed porosity (epsilon) = 0.3100, gravity (g) = 9.8300 m/s^2, fluid density (rho) = 1,030 kg/m^3, particle diameter (D_p) = 0.0068 m, bed depth (L) = 0.4000 m, head loss (h_f) = 3.3580 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning V = 0.9644 m/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 1.9289 — kept a factor of two that cancels in the correct rearrangement.
- 0.4822 — dropped that same factor in the other direction.
- 1.0609 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed used in a water treatment column Given dynamic viscosity (mu) = 0.0008 Pa*s; bed porosity (epsilon) = 0.5200; superficial velocity (V) = 0.0480 m/s; gravity (g) = 9.7900 m/s^2; fluid density (rho) = 1,050 kg/m^3; particle diameter (D_p) = 0.0040 m; head loss (h_f) = 1.6330 m, determine the bed depth (L) in m.
Given
Find
bed depth (L), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except L is given, so isolate L symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that L stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0008 Pa*s, bed porosity (epsilon) = 0.5200, superficial velocity (V) = 0.0480 m/s, gravity (g) = 9.7900 m/s^2, fluid density (rho) = 1,050 kg/m^3, particle diameter (D_p) = 0.0040 m, head loss (h_f) = 1.6330 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning L = 28.4566 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 56.9132 — kept a factor of two that cancels in the correct rearrangement.
- 14.2283 — dropped that same factor in the other direction.
- 31.3023 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed of granular filter media Given dynamic viscosity (mu) = 0.0016 Pa*s; bed porosity (epsilon) = 0.3100; superficial velocity (V) = 0.0250 m/s; gravity (g) = 9.8200 m/s^2; fluid density (rho) = 870.0 kg/m^3; particle diameter (D_p) = 0.0086 m; bed depth (L) = 2.7500 m, determine the head loss (h_f) in m.
Given
Find
head loss (h_f), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except h_f is given, so isolate h_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h_f stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0016 Pa*s, bed porosity (epsilon) = 0.3100, superficial velocity (V) = 0.0250 m/s, gravity (g) = 9.8200 m/s^2, fluid density (rho) = 870.0 kg/m^3, particle diameter (D_p) = 0.0086 m, bed depth (L) = 2.7500 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h_f = 0.4173 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.8346 — kept a factor of two that cancels in the correct rearrangement.
- 0.2087 — dropped that same factor in the other direction.
- 0.4591 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed reactor with spherical particles Given dynamic viscosity (mu) = 0.0015 Pa*s; bed porosity (epsilon) = 0.5300; gravity (g) = 9.8400 m/s^2; fluid density (rho) = 1,070 kg/m^3; particle diameter (D_p) = 0.0090 m; bed depth (L) = 1.2500 m; head loss (h_f) = 2.1130 m, determine the superficial velocity (V) in m/s.
Given
Find
superficial velocity (V), in m/s
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that V stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0015 Pa*s, bed porosity (epsilon) = 0.5300, gravity (g) = 9.8400 m/s^2, fluid density (rho) = 1,070 kg/m^3, particle diameter (D_p) = 0.0090 m, bed depth (L) = 1.2500 m, head loss (h_f) = 2.1130 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning V = 4.3182 m/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8.6364 — kept a factor of two that cancels in the correct rearrangement.
- 2.1591 — dropped that same factor in the other direction.
- 4.7500 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed used in a water treatment column Given dynamic viscosity (mu) = 0.0019 Pa*s; bed porosity (epsilon) = 0.4500; superficial velocity (V) = 0.0010 m/s; gravity (g) = 9.8700 m/s^2; fluid density (rho) = 870.0 kg/m^3; particle diameter (D_p) = 0.0022 m; head loss (h_f) = 1.0040 m, determine the bed depth (L) in m.
Given
Find
bed depth (L), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except L is given, so isolate L symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that L stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0019 Pa*s, bed porosity (epsilon) = 0.4500, superficial velocity (V) = 0.0010 m/s, gravity (g) = 9.8700 m/s^2, fluid density (rho) = 870.0 kg/m^3, particle diameter (D_p) = 0.0022 m, head loss (h_f) = 1.0040 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning L = 44.1045 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 88.2090 — kept a factor of two that cancels in the correct rearrangement.
- 22.0522 — dropped that same factor in the other direction.
- 48.5149 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed of granular filter media Given dynamic viscosity (mu) = 0.0007 Pa*s; bed porosity (epsilon) = 0.5600; superficial velocity (V) = 0.0090 m/s; gravity (g) = 9.7500 m/s^2; fluid density (rho) = 1,110 kg/m^3; particle diameter (D_p) = 0.0092 m; bed depth (L) = 1.5000 m, determine the head loss (h_f) in m.
Given
Find
head loss (h_f), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except h_f is given, so isolate h_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h_f stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0007 Pa*s, bed porosity (epsilon) = 0.5600, superficial velocity (V) = 0.0090 m/s, gravity (g) = 9.7500 m/s^2, fluid density (rho) = 1,110 kg/m^3, particle diameter (D_p) = 0.0092 m, bed depth (L) = 1.5000 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h_f = 0.0017 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0034 — kept a factor of two that cancels in the correct rearrangement.
- 0.0009 — dropped that same factor in the other direction.
- 0.0019 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed reactor with spherical particles Given dynamic viscosity (mu) = 0.0014 Pa*s; bed porosity (epsilon) = 0.5400; gravity (g) = 9.8300 m/s^2; fluid density (rho) = 860.0 kg/m^3; particle diameter (D_p) = 0.0066 m; bed depth (L) = 1.4500 m; head loss (h_f) = 4.5030 m, determine the superficial velocity (V) in m/s.
Given
Find
superficial velocity (V), in m/s
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except V is given, so isolate V symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that V stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0014 Pa*s, bed porosity (epsilon) = 0.5400, gravity (g) = 9.8300 m/s^2, fluid density (rho) = 860.0 kg/m^3, particle diameter (D_p) = 0.0066 m, bed depth (L) = 1.4500 m, head loss (h_f) = 4.5030 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning V = 4.0525 m/s to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 8.1049 — kept a factor of two that cancels in the correct rearrangement.
- 2.0262 — dropped that same factor in the other direction.
- 4.4577 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed used in a water treatment column Given dynamic viscosity (mu) = 0.0016 Pa*s; bed porosity (epsilon) = 0.3200; superficial velocity (V) = 0.0330 m/s; gravity (g) = 9.8900 m/s^2; fluid density (rho) = 1,090 kg/m^3; particle diameter (D_p) = 0.0050 m; head loss (h_f) = 1.0040 m, determine the bed depth (L) in m.
Given
Find
bed depth (L), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except L is given, so isolate L symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that L stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0016 Pa*s, bed porosity (epsilon) = 0.3200, superficial velocity (V) = 0.0330 m/s, gravity (g) = 9.8900 m/s^2, fluid density (rho) = 1,090 kg/m^3, particle diameter (D_p) = 0.0050 m, head loss (h_f) = 1.0040 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning L = 2.4210 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 4.8421 — kept a factor of two that cancels in the correct rearrangement.
- 1.2105 — dropped that same factor in the other direction.
- 2.6632 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed
flow through a packed bed of granular filter media Given dynamic viscosity (mu) = 0.0008 Pa*s; bed porosity (epsilon) = 0.4100; superficial velocity (V) = 0.0090 m/s; gravity (g) = 9.7300 m/s^2; fluid density (rho) = 870.0 kg/m^3; particle diameter (D_p) = 0.0082 m; bed depth (L) = 2.7500 m, determine the head loss (h_f) in m.
Given
Find
head loss (h_f), in m
Start with the thinking
- The governing relation printed in this handbook section is Flow through a packed bed (Ergun-type head loss).
- Everything except h_f is given, so isolate h_f symbolically first — never rearrange after the numbers are in.
- Tabulate each given with its unit and confirm the units are consistent with the relation before substituting.
- Flow through a packed bed filter or reactor obeys a Darcy/Ergun-type head loss relation with the bed porosity.
Step-by-step solution
Step 1 — State the governing relation:
Step 2 — Rearrange the relation so that h_f stands alone on the left-hand side.
Step 3 — List the givens: dynamic viscosity (mu) = 0.0008 Pa*s, bed porosity (epsilon) = 0.4100, superficial velocity (V) = 0.0090 m/s, gravity (g) = 9.7300 m/s^2, fluid density (rho) = 870.0 kg/m^3, particle diameter (D_p) = 0.0082 m, bed depth (L) = 2.7500 m.
Step 4 — Substitute the given values into the rearranged relation.
Step 5 — Evaluate:
Step 6 — Check: returning h_f = 0.0264 m to
reproduces the given quantities, and both sides carry the same units.
Why the other options are there
- 0.0527 — kept a factor of two that cancels in the correct rearrangement.
- 0.0132 — dropped that same factor in the other direction.
- 0.0290 — rounded an intermediate value before the final step.
Reference: FE Handbook — Flow Through a Packed Bed