The ratioNf / Nd is known as shape-factor where Nf is the number of fl...
The shape of flow net character depends only on the type of soil available at the site. Similarly, flow-net once formed is only on the basis of type of soil and its properties. It has no influence in the upstream and downstream heads, dimension of flow space and head difference causing the flow.
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The ratioNf / Nd is known as shape-factor where Nf is the number of fl...
The shape of the flow field changes with soil for anisotropic soil the flow field will be rectangular and for isotropic it will be square henceforth the distances b and a will also change as per the shape of the flow field all in all effecting the b/a ratio hence answer is B.
The ratioNf / Nd is known as shape-factor where Nf is the number of fl...
Shape factor and its relation to b/a ratio:
The shape factor of a flow net is defined as the ratio of the number of flow channels (Nf) to the equipotential drop (Nd). It is denoted as Nf/Nd. The flow net consists of a series of flow channels and equipotential lines that represent the flow of water through the soil. The b/a ratio refers to the ratio of the distance between two consecutive flow lines (b) to the distance between two consecutive equipotential lines (a). It is assumed to be constant throughout the flow net.
Effect of changing the soil in the flow space:
When the soil in the flow space is changed, it affects the hydraulic conductivity and permeability of the soil. The hydraulic conductivity determines how easily water can flow through the soil, and the permeability determines the ability of the soil to transmit water. When the soil properties change, the flow pattern and flow channels in the flow net can be altered.
Impact on the shape factor:
The shape factor is dependent on the flow pattern and the number of flow channels in the flow net. When the soil in the flow space is changed, it can lead to a different flow pattern and distribution of flow channels. This, in turn, affects the shape factor of the flow net. The change in soil properties can result in a different Nf/Nd ratio, indicating a change in the shape factor.
Importance of constant b/a ratio:
The assumption of a constant b/a ratio is made to simplify the construction and interpretation of flow nets. It allows for a consistent spacing between flow lines and equipotential lines, making it easier to visualize and analyze the flow pattern. By maintaining a constant b/a ratio, the flow net can be scaled up or down without affecting the overall shape factor.
Conclusion:
In conclusion, the shape factor of a flow net will change if the soil in the flow space is changed. This is because the change in soil properties can lead to a different flow pattern and distribution of flow channels. The assumption of a constant b/a ratio is important in maintaining a consistent spacing between flow lines and equipotential lines, allowing for easier visualization and analysis of the flow net.
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