# US 4,391,137 A · Groundwater flow meter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 4,391,137 A - Document ID: US4391137A - Status: Granted - Kind: A - Application number: 06/276,787 - Filed: 1981-06-24 - Granted: 1983-07-05 - Earliest claimed: 1980-06-28 - Assignees: K-V Associates, Inc. - Inventors: William B. Kerfoot; Stuart M. Skinner, Jr. - Web page: https://patentgrep.com/patent/US4391137A ## CPC - G01P 13/006: {by using thermal variables} - G01P 5/10: by measuring thermal variables - G01P: MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT (measuring or recording blood flow A61B5/02, A61B8/06; monitoring speed or deceleration of electrically-propelled vehicles B60L3/00; vehicle lighting systems adapted to indicate speed B60Q1/54; determining position or course in navigation, measuring ground distance in geodesy or surveying G01C; combined measuring devices for measuring two or more variables of movement G01C23/00; measuring velocity of sound G01H; measuring velocity of light G01J7/00; measuring direction or velocity of solid objects by reception or emission of radiowaves or other waves and based on propagation effects, e.g. Doppler effect, propagation time, direction of propagation, G01S; measuring speed of nuclear radiation G01T; measuring acceleration of gravity G01V; {measuring or recording the speed of trains B61L23/00; speed indicators incorporated in motor vehicles B60K35/00; measuring frequency or phase G01R; traffic control G08G}) ## Abstract Flow characteristics of a fluid through a permeable solid medium are determined by introducing a predetermined quantity of thermal energy at a highly localized point within the medium and subsequently mapping temperatures around such point to determine the direction and rate of fluid flow through the medium. ## Claims ### Claim 1 The method of measuring a flow characteristic of a fluid, which comprises the steps of: (a) providing a heat conductive porous medium; (b) heating a localized region of said heat conductive porous medium through which fluid is flowing, the heat conductivity of the porous medium being substantially greater than the heat conductivity of the fluid; and (c) measuring the temperature of the medium at at least two regions spaced from said localized region and determining a flow characteristic of the fluid therefrom. ### Claim 2 The method of measuring a flow characteristic of a fluid, which comprises the steps of: (a) heating a localized region of a heat conductive medium through which fluid is flowing, the heat conductivity of the medium being substantially greater than the heat conductivity of the fluid; (b) measuring the temperature of the medium at at least two regions spaced from said localized region and determining a flow characteristic of the fluid therefrom, and the heating of step (a) is effected by heating the medium for a short period of time at said localized region and effecting step (b) subsequent to such heating. ### Claim 3 (depends on 1, 2) The method as defined in claim 1 or 2 wherein the measurement step is made by temperature sensing means displaced from said location. ### Claim 4 (depends on 3) The method as defined in claim 3 wherein said temperature sensing means are arranged in an array surrounding said location. ### Claim 5 (depends on 1, 2) The method as defined in claim 1 or 2 wherein the measurement step is a peak temperature measurement. ### Claim 6 The method of measuring flow characteristics of a fluid, which comprises the steps of: (a) establishing a thermal field in a porous medium disposed within the fluid under test, the heat conductivity of the medium being at least 10 times greater than the heat conductivity of the fluid; (b) measuring temperature peaks within different regions of the thermal field; and (c) determining a flow characteristic of the fluid from the measurements of step (b). ### Claim 7 (depends on 6) The method as defined in claim 6 wherein the flow characteristic determined in step (c) is flow direction. ### Claim 8 (depends on 6) The method as defined in claim 6 wherein the flow characteristic determined in step (c) is flow velocity. ### Claim 9 (depends on 6) The method as defined in claim 6 wherein both flow direction and flow velocity are determined in step (c). ### Claim 10 (depends on 9) Apparatus as defined in claim 9 wherein said first means comprises a heater and circuitry for energizing said heater for a predetermined time. ### Claim 11 (depends on 9) Apparatus as defined in claim 9 wherein said first means comprises a heater and said second means comprises a plurality of temperature sensors arrayed symmetrically with respect to said heater. ### Claim 12 The method of measuring the direction of flow of a fluid, which comprises the steps of: (a) positioning a porous medium in the flowing fluid, said medium having an array of temperature sensors therein and having heat conductivity much greater than that of the fluid; (b) heating the medium for a short period of time at a localized position spaced from said sensors; (c) measuring the temperature peaks at said sensors due to the heat applied in step (a) subsequent to cessation of the heating of step (b); and (d) determining the direction of fluid flow from the measurements of step (c). ### Claim 13 (depends on 9, 12) Apparatus as defined in claim 9 or 12 wherein said second means comprises an array of temperature sensors disposed within said medium. ### Claim 14 (depends on 13) Apparatus according to claim 13 wherein said second means also includes means for determining peak temperature differentials between certain pairs of said sensors. ### Claim 15 The method of measuring the direction and rate of flow of a fluid, which comprises the steps of: (a) positioning a porous medium in the flowing fluid, said medium having an array of temperature sensors therein and having heat conductivity much greater than that of the fluid; (b) heating the medium for a short period of time at a localized position spaced from said sensors; (c) measuring the temperature peaks at said sensors due to the heat applied in step (b) subsequent to cessation of the heating of step (b); and (d) determining the direction and rate of flow of the fluid from the measurements of step (c). ### Claim 16 The method of measuring the rate of flow if a fluid, which comprises the steps of: (a) positioning a porous medium in the flowing fluid, said medium having a pair of temperature sensors therein which are spaced apart in the direction of flow of the fluid whose flow rate is to be measured and having heat conductivity much greater than that of the fluid; (b) heating the medium for a short period of time at a localized position spaced between said temperature sensors; (c) measuring the peak temperature differential between said sensors due to the heat applied in step (b) subsequent to cessation of the heating of step (b); and (d) determining the rate of fluid flow from the measurement of step (c). ### Claim 17 (depends on 16) Apparatus as defined in claim 16 wherein said first means comprises a heater and circuitry for energizing said heater for a predetermined time. ### Claim 18 (depends on 11, 17) Apparatus according to claim 11 or 17 wherein said second means also includes means for determining peak temperature differentials between certain pairs of said sensors. ### Claim 19 The method of obtaining a linear measurement of capillary groundwater flow which comprises the steps of: (a) providing a porous mass composed of uniform spherical particles having a diameter within the range of 0.1-1.0 mm and a heat conductivity of at least 10 times that of water and having an array of heat sensors embedded therein and a heating source centrally disposed among said sensors; (b) embedding the porous mass within the ground so as to be exposed to groundwater flow; (c) energizing said source for a predetermined time; (d) measuring the peak differentials in temperature exhibited between diametrically opposed sensors of said arrays; and (e) determining groundwater flow as a linear function of the maximum peak differential measured in step (d). ### Claim 20 (depends on 19) The method as defined in claim 19 including the step of orienting the array, in step (b), such that the azimuths of diametrically opposed pairs of sensors is known and including the additionally step of determining groundwater flow direction in step (e).